A abampere (aA) The unit of electric current in the CGSeniu system, defined as that current that, if flowing through two parallel conductors of negligible cross section and infinite length, placed 1 cm apart in vacuo, would produce on each conductor a force of 1 dyne per centimeter of length. 1 abampere = 1 abcoulomb/s = r statampere (where c = speed of light in cm/s) = 10 ampere. aberration Imperfect image formation due to geometric imperfections in the optical elements of a system ablation 1 . The wasting of glacier ice by any process (calving, melting, evaporation, etc.). 2. The shedding of molten material from the outer sur- face of a meteorite or tektite during its flight through the atmosphere. absolute age The age of a natural substance, of a fossil or living organism, or of an artifact, obtained by means of an absolute dating method. See absolute dating method. absolute density Density in kg/m' or, more commonly, in g/cm\ both at STP. Cf. density, relative density abso
Metals and non-metals class 10 chemistry NCERT MCQ & SAQ
Metals and non-metals class 10 chemistry NCERT solution:
1. Give an example of a metal which
(i) is a liquid at room temperature.
► Mercury
(ii) can be easily cut with a knife.
► Sodium
(iii) is the best conductor of heat.
► Silver
(iv) is a poor conductor of heat.
► Mercury and Lead
2.Explain the meanings of malleable and ductile.
Answer
Malleable:Substances that can be beaten into thin sheets are called malleable. For example, most of the metals are malleable.
Ductile: Substances that can be drawn into thin wires are called ductile. For example, most of the metals are ductile.
Page no: 46
1. Why is sodium kept immersed in kerosene oil?
Answer
Sodium is a highly reactive element. If it is kept in the open it can explosively react with oxygen to catch fire. Hence to prevent accidental damage sodium is immersed in kerosene oil.
2. Write equations for the reactions of
(i) iron with steam
(ii) calcium and potassium with water
Answer
(i) 3Fe (s) + 4H2O (g) → Fe3O4 (aq) + 4H2 (g)
(ii) Ca (s) + 2H2O (l) → Ca(OH)2 (aq) + H2 (g) + Heat
2K (s) + 2H2O (l) → 2KOH (aq) + H2 (g) + Heat
3. Samples of four metals A, B, C and D were taken and added to the following solution one by one. The results obtained have been tabulated as follows.
Use the Table above to answer the following questions about metals A, B, C and D.
(i) Which is the most reactive metal?
(ii) What would you observe if B is added to a solution of copper (II) sulfate?
(iii) Arrange the metals A, B, C and D in the order of decreasing reactivity.
Answer
(i) B is the most reactive metal.
(ii) B will displace copper from copper sulfate.
(iii) Arrangement of metals in the order of decreasing reactivity B>A>C>D.
4. Which gas is produced when dilute hydrochloric acid is added to a reactive metal? Write the chemical reaction when iron reacts with dilute H2SO4.
Answer
Hydrogen gas is evolved when dilute hydrochloric acid is added to a reactive metal.
When iron reacts with dilute H2SO4, iron (II) sulfate with the evolution of hydrogen gas is formed.
Fe (s) + H2SO4 (aq) → FeSO4 (aq) + H2 (g)
5. What would you observe when zinc is added to a solution of iron (II) sulfate? Write the chemical reaction that takes place.
Answer
When zinc is added to iron (II) sulfate then it will displace the iron from iron sulfate solution as shown in the following chemical reaction.Zn (s) + FeSO4 (aq) → ZnSO4 (aq) + Fe (s)
Page No: 49
1. (i) Write the electron-dot structures for sodium, oxygen and magnesium.
(ii) Show the formation of Na2O and MgO by the transfer of electrons.
(iii) What are the ions present in these compounds?
Answer
(i) The representation of elements with valence electrons as dots around the elements is referred to as electron-dot structure for elements.
(ii)
(iii) The ions present in Na2O are Na+ and O2- ions and in MgO are Mg2+ and O2- ions.
2. Why do ionic compounds have high melting points?
Answer
Ionic compounds have strong electrostatic forces of attraction between the ions. Therefore, it requires a lot of energy to overcome these forces. That is why ionic compounds have high melting points.
Page No: 53
1. Define the following terms.
(i) Mineral (ii) Ore (iii) Gangue
Answer
(i) Mineral: The naturally occurring compounds of elements are known as Mineral.
(ii) Ore: Minerals from which metals can be extracted profitably are known as ores.
(iii) Gangue: The impurities present in the ore such as sand, rocks etc are known as gangue.
2. Name two metals which are found in nature in the free state.
Answer
The metals at the bottom of the reactivity series are mostly found in free state. For example: gold, silver, and platinum.
3. What chemical process is used for obtaining a metal from its oxide?
Answer
A metal can be extracted from its oxide by the process of reduction.
Page No: 55
1. Metallic oxides of zinc, magnesium and copper were heated with the following metals.
In which cases will you find displacement reactions taking place?
Answer
2. Which metals do not corrode easily?
Answer
Metals which have low reactivity such as silver and gold do not corrode easily.
3. What are alloys?
Answer
An alloy is the homogeneous mixture of two or more metals or metals and non metals. For example brass is an alloy of copper and zinc.
1. Which of the following pairs will give displacement reactions?
(a) NaCl solution and copper metal
(b) MgCl2solution and aluminum metal
(c) FeSO4solution and silver metal
(d) AgNO3solution and copper metal.
► (d) AgNO3solution and copper metal.
2. Which of the following methods is suitable for preventing an iron frying pan from rusting?
(a) Applying grease
(b) Applying paint
(c) Applying a coating of zinc
(d) all of the above.
► (c) Applying a coating of zinc
3. An element reacts with oxygen to give a compound with a high melting point. This compound is also soluble in water. The element is likely to be
(a) calcium
(b) carbon
(c) silicon
(d) iron
► (a) calcium
4. Food cans are coated with tin and not with zinc because
(a) zinc is costlier than tin.
(b) zinc has a higher melting point than tin.
(c) zinc is more reactive than tin.
(d) zinc is less reactive than tin.
► (c) zinc is more reactive than tin.
5. You are given a hammer, a battery, a bulb, wires and a switch.
(a) How could you use them to distinguish between samples of metals and non-metals?
(b) Assess the usefulness of these tests in distinguishing between metals and nonmetals.
Anwer
(a) With the hammer, we can beat the sample and if it can be beaten into thin sheets (that is, it is malleable), then it is a metal otherwise a non-metal. Similarly, we can use the battery, bulb, wires, and a switch to set up a circuit with the sample. If the sample conducts electricity, then it is a metal otherwise a non-metal.
(b) The above tests are useful in distinguishing between metals and non-metals as these are based on the physical properties. No chemical reactions are involved in these tests.
6. What are amphoteric oxides? Give two examples of amphoteric oxides.
Answer
Those oxides that behave as both acidic and basic oxides are called amphoteric oxides.
Examples: aluminum oxide (Al2O3), zinc oxide (ZnO)
7. Name two metals which will displace hydrogen from dilute acids, and two metals which will not.
Answer
Iron and aluminum will displace hydrogen from dilute acids as they are more reactive than hydrogen. Mercury and copper cannot displace hydrogen from dilute acids as they are less reactive than hydrogen.
Page No: 57
8. In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
Answer
In the electrolytic refining of a metal M:
Anode → Impure metal M
Cathode → Thin strip of pure metal M
Electrolyte → Solution of salt of the metal M
9. Pratyush took sulfur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it, as shown in figure below.
(a) What will be the action of gas on
(i) dry litmus paper?
(ii) moist litmus paper?
(b) Write a balanced chemical equation for the reaction taking place.
Answer
(a)
(i) There will be no action on dry litmus paper.
(ii) The color of litmus paper will turn red because sulfur is a non-metal and the oxides of non-metal are acidic in nature.
(b) S (s) + O2(g) → SO2 (g)
10. State two ways to prevent the rusting of iron.
Answer
Two ways to prevent the rusting of iron are:
→ Oiling, greasing, or painting: By applying oil, grease, or paint, the surface becomes waterproof and the moisture and oxygen present in the air cannot come into direct contact with iron. Hence, rusting is prevented.
→ Galvanisation:An iron article is coated with a layer of zinc metal, which prevents the iron from coming in contact with oxygen and moisture. Hence, rusting is prevented.
11. What type of oxides are formed when nonmetals combine with oxygen?
Answer
When non-metals are combined with oxygen then neutral or acidic oxides are formed. Examples of acidic oxides are NO2, SO2 and examples of neutral oxides are NO, CO etc.
12. Give reasons
(a) Platinum, gold and silver are used to make jewelry.
(b) Sodium, potassium and lithium are stored under oil.
(c) Aluminum is a highly reactive metal, yet it is used to make utensils for cooking.
(d) Carbonate and sulfide ores are usually converted into oxides during the process of extraction.
Answer
(a) Platinum, gold, and silver are used to make jewelry because they are very lustrous. Also, they are very less reactive and do not corrode easily.
(b) Sodium, potassium, and lithium are very reactive metals and react very vigorously with air as well as water.Therefore, they are kept immersed in kerosene oil in order to prevent their contact with air and moisture.
(c) Though aluminum is a highly reactive metal, it is resistant to corrosion. This is because aluminum reacts with oxygen present in air to form a thin layer of aluminum oxide. This oxide layer is very stable and prevents further reaction of aluminum with oxygen. Also, it is light in weight and a good conductor of heat. Hence, it is used to make cooking utensils.
(d) Carbonate and sulfide ores are usually converted into oxides during the process of extraction because metals can be easily extracted from their oxides rather than from their carbonates and sulfides.
13. You must have seen tarnished copper vessels being cleaned with lemon or tamarind juice. Explain why these sour substances are effective in cleaning the vessels.
Answer
Copper reacts with moist carbon dioxide in air to form copper carbonate and as a result, the copper vessel loses its shiny brown surface forming a green layer of copper carbonate. The citric acid present in the lemon or tamarind neutralizes the base copper carbonate and dissolves the layer. That is why tarnished copper vessels are cleaned with lemon or tamarind juice to give the surface of the copper vessel its characteristic luster.
14. Differentiate between metal and non-metal on the basis of their chemical properties.
Answer
15. A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset but after a futile argument the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
Answer
The solution he had used was Aqua regia. Aqua regia is a Latin word which means ‘Royal Water’. It is the mixture of concentrated Hydrochloric acid and concentrated nitric acid in the ratio of 3:1. It is capable of dissolving metals like Gold and Platinum. Since the outer layer of the gold bangles is dissolved in aqua regia, their weight was reduced drastically.
16. Give reasons why copper is used to make hot water tanks and not steel (an alloy of iron).
Answer
Copper does not react with cold water, hot water, or steam. However, iron reacts with steam. If the hot water tanks are made of steel (an alloy of iron), then iron would react vigorously with the steam formed from hot water. 3Fe + 4H2O → Fe3O4 + H2O
That is why copper is used to make hot water tanks, and not steel.
Metals and non-metals class 10 chemistry NCERT MCQ :
Question : Which is the least conductor of heat
a) Lead
b) Gold
c) Platinum
d) Silver
Answer : Lead
Question : Metal have ______no. of electrons in their outermost shell
a) 1 to 3
b) 1 to 8
c) 7 to 9
d) 10 to 12
Answer : 1 to 3
Question : Which oxide is neutral ?
a) H2O
b) NO2
c) MgO
d) None of these
Answer : H2O
Question : Al2o3 2SiO2.2H2O is the chemical formula of
a) China Clay
b) Bauxite
c) Hematite
d) Monazite
Answer : China Clay
Question : An alloy is
a) A mixture
b) A metalloid
c) A element
d) An isomer
Answer : A mixture
Question : Which nonmetal is the best conductor of electricity
a) Graphite
b) Phosphorus
c) Phosphorus
d) Bromine
Answer : Graphite
Question : Which compound is used in photography
a) AgBr
b) AgO
c) AgCl
d) AgNO3
Answer : AgBr
Question : Carnallite is the mineral of
a) Mg
b) Na
c) Ca
d) All of these
Answer : Mg
Question : The magnesium is used in
a) All of these
b) Grignard reagent
c) Flash bulb
d) Electron alloy
Answer : All of these
Question : Cinnabar is an ore of
a) Mercury
b) Calcium
c) Copper
d) Lead
Answer : Mercury
Question : The constituent of hemoglobin is
a) Iron
b) Copper
c) Sodium
d) Magnesium
Answer : Iron
Question : The most abundant metal in the earth crust is
a) Al
b) O
c) Fe
d) Cu
Answer : Al
Question : Because of high electropositivity, the atom of metals can easily form
a) Positive ions
b) Negatively ions
c) Neutral ions
d) Covalent bonds
Answer : Positive ions
Question : Volatile metals are purified by
a) Distillation
b) Oxidation
c) Liquation
d) Electrolytic refining
Answer : Distillation
Question : Amalgam is the homogeneous mixture of
a) Metal and mercury
b) Metal and non-metal
c) Metal and metal
d) All of these
Answer : Metal and mercury
Question : Which of the following is a ferrous alloy
a) Steel
b) Brass
c) Solder
d) Magnalium
Answer : Steel
Question : Which of the following statements is correct
a) All minerals are ores
b) All ores are minerals
c) All ores are minerals
d) None is correct
Answer : All minerals are ores
Question : Food cans are coated with tin and not zinc because
a) Zinc is more reactive than tin
b) Zinc is less reactive than tin
c) Zinc has a higher melting point than tin
d) Zinc is costlier than tin
Answer : Zinc is more reactive than tin
Question : Elements with atomic number greater than 92 are also called
a) transuranic elements
b) noble gas elements
c) alkaline earth metals
d) alkali metals
Answer : transuranic elements
Question : A purple-coloured solid halogen is
a) I
b) CI
c) Br
d) F
Answer : I
Question : Chalcogen refers to
a) ore-forming elements
b) chemically inert elements
c) salt-forming elements
d) alkali-forming elements
Answer : ore-forming elements
Question : Which of the following is solid at STP?
a) iodine
b) chlorine
c) fluorine
d) bromine
Answer : iodine
Question : Element M is a metal and its chloride has the formula MCl2. The element most likely belongs to which group of the periodIC table'?[
a) 2
b) 17
c) 1
d) 15
Answer : 2
Question : Copper is extracted from low grade ore by
a) hydrometallurgy
b) pyrometallurgy
c) electrometallurgy
d) all of the above processes
Answer : hydrometallurgy
Question : Roasting process is applied to which of the following ores?
a) all of these
b) iron pyrites
c) galena
d) copper glance
Answer : all of these
Question : Purification of metals by liquation method is based on difference in
a) melting point
b) vapor density
c) density
d) solubility
Answer : melting point
Question : Arrange the following metal in the increasing order of their reactivity towards water: Zinc, Iron, Magnesium, Sodium
a) iron < zinc < magnesium < sodium
b) magnesium < iron < sodium < zinc
c) sodium < iron < magnesium < zinc
d) iron < Magnesium < sodium < zinc
Answer : iron < zinc < magnesium < sodium
Question : Which of the following is used for making magnets
a) alnico
b) magnalium
c) duralumin
d) bronze
Answer : alnico
Question : White phosphorus is stored in
a) water
b) ether
c) alcohol
d) kerosene oil
Answer : water
Question : Ordinary glass is a mixture of
a) sodium silicate, calcium silicate
b) sodium silicate, calcium silicate and silica
c) sodium silicate and silica
d) none of the above
Answer : sodium silicate, calcium silicate
Question : Annealing is done to
a) decrease brittleness
b) increase refractive index
c) increase Transparency
d) increase brittleness
Answer : decrease brittleness
Question : Polymer used in making floor tiles is
a) polyvinyl chloride
b) teflon
c) polypropylene
d) buta-1, 3-diene
Answer : polyvinyl chloride
Question : Which of the following is an example of condensation polymers?
a) nylon
b) neoprene
c) polyethene
d) teflon
Answer : nylon
Question : Insulation of electric wire is done by
a) vinyl chloride
b) isoprene
c) neoprene
d) buta-1, 3-diene
Answer : vinyl chloride
Question : Permanent magnets can be made from
a) Wrought iron
b) Cobalt steel
c) Ni steel
d) Stainless steel
Answer : Wrought iron
Question : The formula of Oleum is
a) H2S2O7
b) H2S2O6
c) H2SO4
d) None of these
Answer : H2S2O7
Question : The main constituents of cement are
a) calcium oxide, silicon dioxide, Aluminum oxide
b) calcium oxide, Iron oxide, Sulfur dioxide
c) magnesium oxide, Silicon dioxide, Aluminum oxide
d) none of these
Answer : calcium oxide, silicon dioxide, Aluminum oxide
Question : Hard glass is prepared by
a) fusing a mixture of potassium carbonate, calcium carbonate and silica
b) fusing a mixture of potassium carbonate and any oxide
c) none of the above
d) fusing a mixture of sodium carbonate, calcium carbonate and silica
Answer : fusing a mixture of potassium carbonate, calcium carbonate and silica
Question : The soap can be hardened by
a) adding sodium carbonate or sodium silicate during its manufacture
b) adding sodium chloride
c) adding potassium hydroxide
d) adding animal fat and coconut oil
Answer : adding sodium carbonate or sodium silicate during its manufacture
Question : Soda Acid fire extinguisher contains
a) sodium hydrogen carbonate and sulphuric acid
b) sodium carbonate and nitric acid
c) sodium carbonate and carbonic acid
d) sodium chloride and sulphuric acid
Answer : sodium hydrogen carbonate and sulphuric acid
Question : The real bleaching agent present in bleaching powder is
a) chlorine
b) oxygen
c) CaO
d) none of the above
Answer : chlorine
Question : Cake does not taste bitter due to presence of
a) tartaric acid
b) citric acid
c) sodium carbonate
d) sugar
Answer : tartaric acid
Question : What is obtained on adding lime to H2O?
a) slaked lime
b) quicklime
c) limestone
d) lime
Answer : slaked lime
Question : The best electrical conductor is
a) silver
b) gold
c) copper
d) aluminum
Answer : silver
Question : "is malleable and ____" This statement best describes,
a) a metal
b) a metalloid
c) a nonmetal
d) a compound
Answer : a metal
Question : The most reactive metal of the following is
a) sodium
b) iron
c) zinc
d) magnesium
Answer : sodium
Question : The reaction, Zinc + Copper sulfate solution → Zinc sulfate solution + Copper, indicates that the metal which appear lower in the reactivity series is
a) Cu
b) Cu2+
c) Zn
d) Zn2+
Answer : Cu
Question : Where do the metals which can displace hydrogen from water at room temperature appear in the reactivity series ?
a) near the top
b) in the middle
c) at the bottom
d) next to hydrogen
Answer : near the top
Question : Iron is galvanized by coating it with
a) zinc
b) chromium
c) nickel
d) manganese
Answer : zinc
Question : Metalloids share the properties of
a) Both
b) Non-metals
c) Metals
d) None of these
Answer : Both
Question : Which one of the following is used for making pencil lead ?
a) Graphite
b) Sulfur
c) Diamond
d) None
Answer : Graphite
Question : The metal that melts even when kept on the palm is
a) Mercury
b) Gallium
c) Cobalt
d) Nickel
Answer : Mercury
Question : Which of the following metals cannot displace hydrogen ?
a) All of these
b) Silver
c) Copper
d) Gold
Answer : All of these
Question : The essential condition required for rusting of iron is the pressure of
a) Moist oxygenated air
b) Nitrogen
c) Moisture
d) Oxygenated air
Answer : Moist oxygenated air
Question : Which of the following elements is a metalloid?
a) Silicon
b) Nitrogen
c) Carbon
d) Calcium
Answer : Silicon
Question : Which of the following is the best conductor of electricity ?
a) Copper
b) Gold
c) Aluminum
d) Mercury
Answer : Copper
Question : The metal liquid at room temperature is
a) Mercury
b) Aluminum
c) Copper
d) Sodium
Answer : Mercury
Question : The element used as the index of the wealth of a country is
a) Gold
b) Platinum
c) Aluminum
d) Mercury
Answer : Gold
Question : The soldering wire is an alloy of
a) Copper and aluminum
b) Aluminum and lead
c) Lead and tin
d) Copper and tin
Answer : Copper and aluminum
Question : The stainless steel is an alloy of
a) Iron, nickel and chromium
b) Nickel and chromium
c) Iron and chromium
d) Iron and nickel
Answer : Iron, nickel and chromium
Question : The best electrical conductor is,
a) gold b) copper
c) silver d) aluminum
Answer : C
Question : "is malleable and ......" This statement best describes,
a) a metal b) a nonmetal
c) a metalloid d) a compound
Answer : A
Question : The most reactive metal of the following is,
a) zinc b) iron
c) magnesium d) sodium
Answer : D
Question : The reaction, Zinc + Copper sulfate solution → Zinc sulfate solution + Copper,indicates that the metal which appear lower in the reactivity series is,
a) Zn b) Cu
c) Zn2+ d) Cu2+
Answer : B
Question : Where do the metals which can displace hydrogen from water at room temperature appear in the reactivity series ?
a) near the top b) at the bottom
c) in the middle d) next to hydrogen
Answer : A
Question : Iron is galvanized by coating it with,
a) nickel b) chromium
c) manganese d) zinc
Answer : D
Question : Metalloids share the properties of
a) Metals b) Non-metals
c) None d) Both
Answer : D
Question : Which one of the following is used for making pencil lead ?
a) Graphite b) Diamond
c) Sulfur d) None
Answer : A
Question : The metal that melts even when kept on the palm is
a) Cobalt b) Gallium
c) Nickel d) Mercury
Answer : D
Question : Which of the following metals cannot displace hydrogen ?
a) Copper b) Silver
c) Gold d) All of these
Answer : D
Question : The essential condition required for rusting of iron is the pressure of
a) Oxygenated air
b) Moisture
c) Nitrogen
d) Moist oxygenated air
Answer : D
Question : Which of the following elements is a metalloid?
a) Carbon b) Nitrogen
c) Calcium d) Silicon
Answer : D
Question : Which of the following is the best conductor of electricity ?
a) Copper b) Aluminum
c) Gold d) Mercury
Answer : A
Question : The metal liquid at room temperature is
a) Copper b) Aluminum
c) Sodium d) Mercury
Answer : D
Question : The element used as the index of the wealth of a country is –
a) Platinum b) Aluminum
c) Gold d) Mercury
Answer : C
Question : The soldering wire is an alloy of
a) Copper and tin
b) Lead and tin
c) Aluminum and lead
d) Copper and aluminum
Answer : D
Question : The stainless steel is an alloy of –
a) Iron and nickel
b) Iron and chromium
c) Nickel and chromium
d) Iron, nickel and chromium
Answer : D
Metals and non-metals class 10 chemistry NCERT SAQ
Explain with an example how the metal (X) which is low in reactivity series and metal (Y) which is high in the reactivity series are obtained from their compounds by reduction process.
(b) Write the electronic configurations of sodium and chlorine. Show the formation of sodium chloride from sodium and chlorine by the transfer of electrons.
(c) List any two observations when a highly reactive metal is dropped in water.
Answer.
(a) ‘X’ is obtained by chemical reduction.
‘Y’ is obtained by electrolytic reduction.
(c) (i) Metal will catch fire.
(ii) Alkali solution is formed which turns red litmus blue.
.With the help of a suitable example, explain how ionic compounds are formed. State any three general properties of ionic compounds.
Answer.Ionic compounds are formed by transfer of electrons from metal to non-metals, e.g.
General Properties:
(i) They are the solids that have a high melting point.
(ii) They are soluble in water.
(iii) They conduct electricity in molten state as well as in aqueous solution.
Elements magnesium and oxygen respectively belong to group 2 and group 16 of the Modern Periodic Table. If the atomic numbers of magnesium and oxygen are 12 and 8 respectively, draw their electronic configurations and show the process of formation of their compound by transfer of electrons.
Answer.(Mg)=2,8,2
Q 1. Explain the following: [Delhi 2019]
(a) Sodium chloride is an ionic compound that does not conduct electricity in a solid state whereas it does conduct electricity in the molten and solid-state as well as in an aqueous solution.
(b) Reactivity of aluminum decreases if it is dipped in nitric acid.
(c) Metals like calcium and magnesium are never found in their free state in nature.
(a)
Sodium chloride is an ionic compound because it is made up of Na+ and CP- ions.
It does not conduct electricity in a solid state because ions are not free to move.
It conducts electricity in a molten state because ions are free to move.
(b) It is due to the formation of an oxide layer on its surface which makes it passive (less reactive) HNO3 is a good oxidizing agent.
(c) It is because Mg and Ca are highly reactive, react with other elements to form compounds, therefore, are not found in a free state.
Q 2. (a) What is the reactivity series? How does the reactivity series help in predicting the relative activity of various metals?
(b) Suggest different chemical processes used for obtaining a metal from its oxides of metals in the middle and top of the reactivity series. Support your answer with one example. [CBSE Sample Paper 2018]
(a) The series of metals in decreasing order of reactivity is called the reactivity series of metals. The metals at the top are most reactive and metals at the bottom are least reactive.
(b) The metals in the middle of the reactivity series are obtained from their ores by chemical reduction with a suitable reducing agent, e.g.
ZnO + C → Zn + CO
The metals at the top of the series are obtained by electrolytic reduction of their molten orc.
Al2O3 → 2Al3+ + 3O2-
At cathode: 2Al3+ + 6e- → 2Al
At anode: O2- - 2e- → O
O + O → O2
Q 3. Explain the following statements: [CBSE 2016]
(a) Most metal oxides are insoluble in water but some of these dissolve in water. What are these oxides and their solutions in water called?
(b) At ordinary temperature the surface of metals such as magnesium, aluminum, zinc, etc. is covered with a thin layer. What is the composition of this layer? State its importance.
(c) Some alkali metals can be cut with a knife.
(a) Solution of metal oxides in water is called alkali (soluble base), e.g. sodium hydroxide (NaOH), potassium hydroxide (KOH).
(b) This layer is an oxide layer. It makes the metal less reactive (passive) and makes it more useful because it cannot get corroded and remains as it is.
(c) It is because these metals are very soft, e.g. sodium metal can be cut with a knife.
Q 4. Write one example of each of the following: [CBSE 2016]
(a) Most malleable metal and most ductile metal.
(b) The best conductor of heat and the poorest conductor of heat.
(c) A metal with the highest melting point and metal with the lowest melting point.
(a) Gold is the most malleable and ductile metal.
(b) Silver is the best conductor, whereas lead is a poor conductor of heat.
(c) Tungsten has the highest melting point, Mercury has the lowest melting point.
Q 5. Write one example of each of the following:
(a) A metal and a non-metal which are liquids at room temperature.
(b) A metal that is very soft and a non-metal which is very hard.
(c) A metal which has a very low melting point and a non-metal which has a very high melting point. [CBSE 2016]
(a) Mercury is a metal, bromine is non-metal, liquid at room temperature.
(b) Sodium is a very soft metal, diamond is a very hard non-metal.
(c) Gallium has a low melting point, diamond has a very high melting point.
Q 6. State two properties of each of the following metals which make them suitable for: [CBSE 2016]
(i) Copper and aluminum for making electric wires.
(ii) Gold, platinum and silver are used to make jewelry.
(iii) Copper to make a hot water tank.
(i) Copper and aluminum are ductile and good conductors of electricity.
(ii) Gold, platinum and silver are malleable and ductile.
(iii) Copper is a malleable and a good conductor of heat.
Q 7. Describe how sodium and chlorine form sodium chloride? Name the type of bonding shown in the structure. (Atomic number : Na - 11, Cl - 17) [CBSE 2016]
Na (2, 8, 1) → Na+ (Sodium Cation) + e-
Cl (2, 8, 7) + e- → Cl- (Chloride Anion)
There is ionic bonding between sodium and chloride ions.
Q 8. Write the names and symbols of the constituents present in the following alloys [CBSE 2016]
(a) Brass
(b) Bronze
(c) Solder
Brass: Copper(Cu) and Zinc(Zn)
Bronze: Copper(Cu) and Tin(Sn)
Solder: Lead(Pb) and Tin(Sn)
Q 9. What is a cinnabar? How is a metal extracted from a cinnabar? Explain briefly. [CBSE 2015]
Cinnabar is HgS
Mercury is obtained by roasting cinnabar. HgO formed is thermally unstable and gives mercury.
2HgS(s) + 3O2(g) → 2HgO(s) + 2SO2(g)
2HgO(s) –Δ→ 2Hg(l) +O2(g)
HgS(s) +O2(g) → Hg(l) + SO2(g)
Mercury can be purified by distillation.
Q 10. (a) Write the electron dot structures for potassium and chlorine.
(b) Show the formation of KCL by the transfer of electrons.
(c) Name the ions present in this compound, KCI. [CBSE 2015]
KCl has K + (Potassium Cation) and Cl- (Chloride Anion).
Q 11. State three reasons for the following facts: [CBSE 2015]
(a) Sulfur is a non-metal
(b) Magnesium is a metal
One of the reasons must be supported with a chemical equation.
Q 12. Why does the oxide of highly reactive metals cannot be reduced by carbon? [CBSE 2015]
It is because highly reactive metals themselves are stronger reducing agents than carbon.
Q 13. What happens when carbon dioxide is compressed in water at higher pressure? [CBSE 2015]
Carbonic acid is formed.
CO2 + H2O → H2CO3
Q 14. Write the chemical equation for the reaction taking place when steam is passed over hot aluminum. [CBSE 2015]
2Al(s) + 3H2O (g) → Al2O3(s) + 3H2(g)
Long Answer Type Questions
Q 1. (a) Write the steps involved in the extraction of pure metals in the middle of the activity series from their carbonate ores.
(b) How is copper extracted from its sulfide ore? Explain the various steps supported by chemical equations. Draw a labeled diagram for the electrolytic refining of copper. [CBSE 2018]
(a) Steps involved:
Taking the case of zinc carbonate:
1. Calcination
2. Reduction
3. Purification is done by electrolytic refining.
(b) Copper is found in nature as Cu2S. It can be obtained from the ore just by heating it in air.
Electrolytic refining of copper is done as shown in the diagram here.
Give reason for the following:
(a) School bells are made up of metals.
(b) Electric wires are made up of copper.
Answer.
(a) It is because metals are sonorous, i.e. they produce sound when struck with a hard substance.
(b) It's because copper is a good conductor of electricity.
Suggest a method of reduction for the following metals during their metallurgical processes:
(i) metal ‘A’ which is one of the last, second or third positions in the reactivity.
(ii) metal ‘B’ which gives a vigorous reaction even with water and air.
(iii) metal ‘C’ which is kept in the middle df activity series.
Answer.
(i) ‘A’ can be obtained by chemical reduction using carbon or carbon monoxide as a reducing agent.
(ii) ‘B’ can be obtained by electrolytic reduction.
(iii) ‘C’ can be reduced by reducing agents like ‘Al’.
Name the following:
(a) A metal, which is preserved in kerosene.
(b) A lustrous coloured non-metal.
(c) A metal, which can melt while kept on the palm.
(d) A metal, which is a poor conductor of heat.
Answer.
(a) Sodium is preserved in kerosene.
(b) Iodine is lustrous coloured non-metal.
(c) Gallium. ‘
(d) Lead.
explain why calcium metal after reacting with water starts floating on its * surface. Write the chemical equation for the reaction. Name one more metal
that starts floating after some time when immersed in water.
Answer. Calcium starts floating because the bubbles of hydrogen gas formed stick to the
surface of metal.
Magnesium reacts with hot water and starts floating due to the bubbles of hydrogen gas sticking to its surface.
Give reason for the following:
(a) Aluminum oxide is considered as an amphoteric oxide.
(b) Ionic compounds conduct electricity in molten state.
Answer.
(a) It is because it reacts with acids as well as bases to produce salts and water.’Al’ is less electropositive metal. So, it forms amphoteric oxide which can react with acid as well as base.
(b) Ionic compounds can conduct electricity in molten state because ions ’ become free to move in molten state.
Explain the formation of ionic compound CaO with electron dot structure. Atomic numbers of calcium and oxygen are 20 and 8 respectively.
(b) Name the constituent metals of bronze.
Answer.
(b) Bronze is made up of copper and tin.
A metal ‘X’ acquires a green color coating on its surface on exposure to air.
(i) Identify the metal ‘X’ and name the process responsible for this change.
(ii)Name and write chemical formula of the green coating formed on the metal.
(iii) List two important methods to prevent the process.
Answer.
(i) Metal is copper. The process is corrosion.
(ii)Basic copper carbonate [CuCO3.Cu(0H)2].
(iii)
• It should be coated with tin
• It should be mixed with other metals to form alloys.
What is meant by ‘rusting’? With labeled diagrams, describe an activity to find out the conditions under which iron rusts.
Answer. The process in which iron reacts with oxygen in the presence of moisture to form reddish brown coating of hydrated ferric oxide [Iron (III) oxide].Fe2O3 xH20
Activity:
(i) Take three boiling tubes A, B and C.
(ii) Pour some water in the test tube. Put iron nails in it and cork it.
(iii) Pour boiled distilled water in another test tube B and put iron nails in it. Add 1 ml of oil over it such that oil floats over it and prevents the air from entering.
(iv) Take some iron nails in test tube C and put some anhydrous calcium chloride in it and cork it.
(v) Leave all the three test tubes for one day and then observe.
Observation: Iron nails get rusted in test tube A because both air and water are present in it. Iron nails do not get rusted in B because there is water but no air. In C, rusting will not take place because there is neither air nor water. Conclusion: Iron gets rusted in the presence of air and water.
The way metals like sodium, magnesium and iron react with air and water is an indication of their relative positions in the ‘reactivity series’. Is this statement true ? Justify your answer with examples.
Answer.Yes, sodium reacts explosively even with cold water, it is most reactive. Magnesium reacts with hot water, it is less reactive than Na. Iron reacts only with steam which shows it is least reactive among the three.
When a metal X is treated with cold water, it gives a base Y with molecular formula XOH (Molecular mass = 40) and liberates a gas Z which easily catches fire. Identify X, Y and Z.
Answer.
50. Write chemical equations that show aluminum oxide reacts with acid as well as base.
Answer.
Metals and non-metals class 10 chemistry NCERT lng question
Distinguish between ionic and covalent compounds under the following properties:
(i) Strength of forces between constituent elements.
(ii) Solubility of compounds in water.
(iii) Electrical conduction in substances.
(b) Explain how the following metals are obtained from their compounds by the reduction process:
(i) Metal M which is in the middle of the reactivity series.
(ii) Metal N which is high up in the reactivity series.
Give one example of each type.
Answer.
(b) (i) Metal M which is in the middle of the reactivity series is reduced by aluminum, e.g.
3MnO2(s) + 4Al(s) ——–> 2Al2O3(s) + 3Mn(l)
(ii) Metal N will be obtained by electrolytic reduction, e.g. A1 is obtained by electrolytic reduction.
What is meant by corrosion? Name any two methods used for the prevention
of corrosion.
(b) Suppose you have to extract metal M from its enriched sulfide ore. If M is in the middle of the reactivity series, write various steps used in extracting this metal.
Answer. (a) Corrosion is a process in which metal reacts with substances present in the environment to form surface compounds.
Prevention:
(i) Galvanisation is a process to prevent corrosion of iron.
(ii)Electroplating is also used to prevent corrosion.
(b)(i) Concentration of ores: Sulfide ore will be concentrated by froth- floatation process. Sulfide ore will be collected in froth whereas gangue will be left behind.
(ii) Roasslng: Sulfide ore is heated strongly in the presence of O2 to form metal oxide and sulfur dioxide.
2MS + 3O2 ————- ► 2MO + 2SO2
(iii) Reduction: MO reacts with carbon (acts as reducing agent) to form metal and CO.
MO + C —-> M + CO
(iv) Electrolytic refining: Impure metal ‘M’ is purified by electrolytic refining. Impure metal is taken as anode, pure metal is taken as cathode, soluble salt of metal is taken as electrolyte. Impure metal forms metal ions which gain electrons and form pure metal at cathode.
(a) Give two methods to prevent the rusting of iron.
(b) Name the ores of the following metals:
(i) mercury, and
(ii) zinc
(c) Explain with the help of a diagram, how copper metal can be refined? Label the important arrangements in the experimental set up.
Answer.
(a)(i) Painting (ii) Galvanisation
(b)(i) Cinnabar (ii) Zinc Blende
(c) Impure copper is taken as anode whereas pure copper is taken as cathode. Copper sulfate solution (CuS04) is taken as electrolyte. When electric current is passed, impure copper changes to ions which gain electrons at cathode and change into pure copper. Impurities are left behind as anode mud.
At anode:
At Cathode:
.(a) How can the metals at the top of the reactivity series be extracted from their ores? Explain with an example.
(b) Name any one alloy made from
(i) a metal and a nonmetal, and
(ii) two metals.
Answer.
(a) These metals are extracted by electrolytic reduction, e.g. aluminum is obtained from bauxite by electrolytic reduction.
(b) (i) Steel is made up of iron and carbon.
(ii) Brass is made up of copper and zinc.
(a) Name the main ore of mercury. How is mercury obtained from its ore? Give a balanced chemical equation.
(b) What is the thermite reaction? How is it used to join the railway tracks or cracked machine parts?
(c) Name the method used to extract metals of high reactivity.
Answer.
(a) Cinnabar
Mercury is obtained from its ore by roasting.
(b) When aluminum is heated with Fe203 to get molten iron, it is called thermite reaction.
Molten iron is used to weld broken railway tracks.
(c) Electrolytic reduction
A metal ‘M’ which is one of the best conductors of heat and electricity used in making electric wires is found in nature as sulfide ore M2S?
(i) Name the metal ‘M’
(ii) Which process will be suitable for extraction of this metal M from its ore M2S? Write the balanced chemical reactions involved in the process of ‘ extraction.
(iii) With the help of a labeled diagram, explain the process of electrolytic refining of the metal.
Answer.
(i) Copper
(ii) It is concentrated by the froth-floatation process.
Impure copper is purified by electrolytic refining.
(iii) Impure metal is taken as anode whereas pure metal is taken as cathode.iSoluble salt of metal is taken as electrolyte. When electric current is passed, impure metal changes to ions which gain electrons at cathode
and change into pure metal. Impurities are left behind as anode mud.
.Write the names and symbols of two most reactive metals. Explain by drawing electronic structure how any one of the two metals react with a halogen. State any four physical properties of the compound formed.
Answer. K(Potassium) and Na(Sodium) are the two most reactive metals. K’ and Na‘ are electronic structures as they have one valence electron.
where ‘F’ is a halogen.
Four physical properties of the compounds formed by these elements and
halogens are:
(i) They have a high melting point.
(ii)They are soluble in water.
(iii) They conduct electricity in molten state
How is the method of extraction of metals high up in the reactivity series different from that for metals in the middle ? Why cannot the same process be applied to them? Explain giving equations, the extraction of sodium.
Answer. Metals high up in the series are obtained by electrolytic reduction because these metals are strong reducing agents and therefore, cannot be obtained by chemical reduction.
Metals in the middle of the series are less reactive and can be obtained by chemical reduction. The same process can not be used for both of them as highly reactive metals can not be obtained by chemical reduction.
Extraction of sodium is done by electrolysis of molten sodium chloride.
(a) Differentiate between roasting and calcination. Explain the two with the help of suitable chemical equations. How is zinc extracted from its ore?
(b) Name two metals that can be used to reduce metal oxides to metals.
Answer.
(a) Roasting: It is a process in which sulfide ore is heated in the presence of oxygen to convert into oxide.
Cali ination: It is a process in which carbonate ore is heated in the absence of air to form oxide.
By reduction process, Zn can be extracted from its ore.
(b) Aluminum, Magnesium.
(a) Write the chemical name of the coating that forms on silver and copper articles when these are left exposed to moist air.
(b) Explain what galvanisation is. What purpose is served by it?
(c) Define an alloy. How are alloys prepared? How do the properties of iron change when:
(i) small quantity of carbon,
(ii) nickel and chromium are mixed with it.
Answer.
(a) Ag2S (silver sulfide) is formed on silver, basic copper carbonate CuCO3. CU(OH)2 is formed on copper.
(b) The process of coating zinc over iron is called galvanisation. It is used to prevent rusting of iron.
(c) Alloy is a homogeneous mixture of two or more metals. One of them can be non-metal. Alloys are prepared by melting two or more metals together.
(?) Iron does not rust by adding a small,quantity of carbon.
(ii) When we form an alloy of iron with nickel and chromium, we get stainless steel which is malleable and does not get rusted.
define an activity series of metals. Arrange the metals gold, copper, iron and magnesium in order of their increase in reactivity.
(b) What will you observe when:
(i) Some zinc pieces are put in copper sulfate solution.
(ii) Some silver pieces are put into a green coloured ferrous sulfate solution.
Answer.
(a) The series of metals in which metals are arranged in decreasing order of their reactivity.
Au < Cu < Fe < Mg is increasing order of reactivity.
(b) (i) The blue solution will become colorless and reddish brown copper metal will be deposited.
Reaction will not take place because Ag’ is less reactive than iron.
Distinguish between metals and nonmetals on the basis of (i) two physical and (ii) three chemical properties. [CBSE 2018 for Blind]
Q 3. (a) Define corrosion. [CBSE 2016]
(b) What is corrosion of iron called?
(c) How will you recognise the corrosion of silver?
(d) Why is corrosion of iron a serious problem?
(e) How can we prevent corrosion of iron?
(a) It is a process in which a metal reacts with substances present in the air to form surface compounds.
(b) Rusting.
(c) Black layer on its surface due to formation of Ag2S.
(d) It makes the metal weak and brittle, which is a serious problem.
(e) Oiling, painting, greasing, galvanisation, alloying can prevent iron from corrosion.
Q 4. (a) Define corrosion, what name is given to the corrosion of iron?
(b) Name the color of the coating formed on silver and copper articles, when exposed to air?
(c) List two damages caused by corrosion and suggest how corrosion can be prevented. [CBSE 2016]
(a) When a metal is attacked by substances around it, such as moisture, acids, etc., it is said to corrode and this process is called corrosion. Corrosion of iron is called rusting.
(b) Coating formed on silver is black and that formed on copper is green.
(c) Damages caused by corrosion:
It causes damage to car bodies and bridges.
It damages iron railings and ships.
Prevention of corrosion:
Corrosion can be prevented by oiling, painting, greasing and galvanizing.
Corrosion can be prevented by galvanizing and alloying.
Q 5. Give reasons for the following: [CBSE 2016]
(i) Carbonate and sulfide ores are usually converted into oxides during the process of extraction of metals.
(ii) Ionic compounds have generally high melting points.
(iii) Hydrogen is not a metal, but it has been assigned a place in the reactivity series of metals.
(iv) The galvanized iron article is protected against rusting even if the zinc layer is broken.
(v) The wires carrying current in homes have a coating of PVC.
(i) It is easier to convert metal oxides to metals as compared to carbonates and sulfides. Therefore carbonates are calcined and sulfides are roasted to oxides.
(ii) There are electrostatic forces of attraction between the cations and anions in ionic compounds which are difficult to break. Therefore ionic compounds have high melting points.
(iii) Metals above hydrogen evolve hydrogen gas and metals below hydrogen do not evolve hydrogen when treated with an acid. That is when hydrogen has been assigned a place in the reactivity series of metals.
(iv) Even if the zinc layer is broken, it will preferentially be oxidized because it is more reactive than iron.
(v) The wires carrying current in homes have a coating of PVC. This is because PVC is an insulating substance and protects from electric shock.
Q 6. (a) Write electron dot structure for chlorine (At No. 17) and calcium (At No. 20). Show the formation of calcium chloride by the transfer of electrons.
(b) Identify the nature of the above compound and explain the three physical properties of such compounds. [CBSE2015]
(b) It is an ionic compound.
Physical properties
(i) It is hard and solid.
(ii) It has a high melting and boiling point.
(iii) It is soluble in water.
Q 7. (a) Describe an activity to show that metals are good conductors of electricity.
(b) Account for the following:
(i) Hydrogen gas is not evolved when a metal reacts with nitric acid.
(ii) For storing sodium metal, it is kept immersed in kerosene.
(iii) The reaction of iron (III) oxide with aluminum is used to join cracked iron part machines. [CBSE 2015]
(a) Activity:
Set up an electric circuit as shown in the figure.
Place the metal to be tested in the circuit between terminals A and B as shown.
We find that the bulb glows. This shows that metals are good conductors of electricity.
(b) (i) This is because the hydrogen gas first evolved reacts with HNO3 to produce oxides of nitrogen.
(ii) We cannot store it underwater because sodium reacts with water to produce hydrogen gas.
2Na + 2H2O → 2NaOH + H2
(iii) Fe2O3 + 2AI → AI2O3 + 2Fe + Heat
This is an exothermic reaction. The molten iron is used to join the cracked iron parts of the machine.
Q 8. (a) When calcium metal is added to water, the gas evolved does not catch fire but the same gas evolved on adding potassium metal to water catches fire. Explain why?
(b) Name a metal for each case :
(i) It displaces hydrogen gas from nitric acid.
(ii) It does not react with any physical state of water.
(iii) It does not react with cold as well as hot water but reacts with steam. [CBSE 2015]
(a) Reaction of potassium with water is so violent and exothermic that the evolved hydrogen catches fire.
2K(s) + 2H2O(l) → 2KOH(aq) + H2(g)
The reaction of calcium with water is less violent. The heat evolved is not sufficient for hydrogen to catch fire.
Ca(s) + 2H2O(l) → Ca(HO)2(aq) + H2(g)
(b) (i) Magnesium
(ii) Copper
(iii) Aluminum
Q 9. (a) In column I, there are given different methods of extraction. Name the methods used for the extraction of metals given in column II:
(b) Differentiate between roasting and calcination processes giving one example of each. [CBSE2015]
(a)
(b)
Q 10. In the formation of a compound XY2, atom X donates one electron to each Y atom. Show the electron dot structure of X and Y and the formation of XY2. What is the nature of the bond in XY2? Write any three properties of compound XY2. The electronic configurations of the elements X and Y are as follows: [CBSE 2015]
X - 2, 8, 2 Y - 2, 7
The nature of bonds in XY2 is ionic.
Properties:
Ionic compounds have high melting and boiling points.
Ionic compounds are generally soluble in water and insoluble in kerosene and petrol.
Solutions of ionic compounds conduct electricity. The molten state of such compounds also conducts electricity.
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