METALS AND NON METALS

1. 3 MARKS QUESTIONS
METALS AND NON METALS
1) State reasons for the following
(a) Electric wires are covered with rubber like material. 1m
(b) Zinc can liberate hydrogen gas with dilute hydrochloric acid but copper
cannot. 1m
(c) Sulphide ore of a metal is first converted to its oxide to extract the metal from
it. 1m
Ans) (a)Rubber is an insulator and can avoid electrolution and short circuit.
(b) Zinc is more reactive than hydrogen so it can displace hydrogen from dilute HCl but copper
is less reactive than hydrogen.
(c) It is easy to reduce oxide ore as compared to sulphide ore to extract a metal from its ore.
2) a) Why are ionic compounds usually hard? 11/2 m
b) Ionic compounds in solid state do not usually conduct electricity but they do so
in molten state. 11/2 m
Ans) a) There is a strong force of attraction between the oppositely charged ions and so they are
hard.
b) Ions are not free to move in solid state where as they move freely in molten state and conduct
electricity.
3) A student was given Mn,Zn,Fe and Cu metals. Identify which of them
a) Will not displace H2 from dilute HCl. 1m
b) Will react only with steam to give H2(g). 1m
c) Will give H2 with 5% HNO3. 1m
Ans) a) Copper will not displace hydrogen from dil. HCl.
b) Iron will react only with steam to liberate H2(g).
3Fe(s)+4H2O(g)  Fe3O4(s) + 4H2(g)
c) Manganese will react with 5% HNO3 to give hydrogen
Mn(s) + 2HNO3 (5%)  Mg(NO3)2(aq) + H2(g)
4) Write balanced equations for the reactions of:
i) Aluminium when heated in air. Write the name of the product. 1m
ii) Iron with steam. Name the product obtained. 1m
iii) Calcium with water. Why does calcium start floating in water? 1m
Ans) i) 4Al (s) + 3O2 (g) 2Al2O3 (s0
The product formed is aluminium oxide.
ii) 3Fe (s)+ 4H2O (g)(Steam)  Fe3O4 (s) + 4H2 (g)
The product obtained is iron(II) (III) oxide.

2. iii) Ca (s)+2H2O (l)  Ca(OH)2 (Aq) + H2 (g)
The bubbles of hydrogen stick to the surface of metal that is why it floats.
5) 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. 1m
ii) Name and write chemical formula of the green coating formed on the metal.
1m
iii) List two important methods to prevent the process. 1m
Ans) i) Metal is Copper. The process is corrosion.
ii) Basic copper carbonate [CuCO3.Cu(OH)2]
iii) It should be coated with tin.
It should be mixed with other metals to form alloys.
6)
Ans)
ii) Reduction: This oxide of metal is reduced with suitable reducing agent to get free metal.
ZnO(s) + C(s)  Zn(s) + CO(g)
7) a) What are amphoteric oxides? Choose the amphoteric oxides from amongst
the following oxides:
Na2O, ZnO, Al2O3, CO2, H2O 11/2 m
b) Why is that non metals do not displace hydrogen from dilute acids? 11/2 m
Ans) a) Metal oxides which are both acidic as well as basic are called amphoteric oxides, e.g.,
Al2O3, ZnO.
b) It is because non-metals do not supply electrons to change H+ ions into hydrogen gas.
8) Name two metals which react violently with cold water. Write any three
observations you would make when such a metal is dropped into water. How
would you identify the gas evolved, if any, during the reaction? 3m
Ans) Sodium, Potassium
When these metals are dropped in water, bubbles will be evolved due to evolution of hydrogen
gas. 1m
The gas will catch fire and the solution will be alkaline, i.e., it will turn red litmus blue. 1m
Test: When a burning matchstick is brought near the gas. It burns exclusively with a ‘pop’ sound
and splinter is extinguished. 1m
9)a) Explain the formation of ionic compound CaO. Atomic number of calcium
and oxygen are 20 and 8 respectively. 11/2 m
b) Name the constituent metals of bronze. 11/2 m
Ans)a) Ca  Ca2+ + 2e-
2, 8, 8, 2 2, 8, 8
O + 2e-  O2-

3. 2, 6 2, 8
(Ca2+) (O2-)
b) Bronze is made up of copper and tin.
10) Name the following:
a) A lustrous colored non-metal. 1m
b)A metal which can melt when kept on arm. 1m
c)A metal, which is poor conductor of heat. 1m
Ans) a) Iodine is a non-metal but it is very lustrous. (Or) Graphite
b) Galium and Caesium have very low melting points, they even melt when kept on palm.
c) Lead is a metal but it is a poor conductor of heat.