Question

4. Define corrosion. Why do iron objects become weak with time
5. Explain the following
a, Copper vessels turn green with the passage of time.
b. Silver objects turn black and lose their lustre with time
c. Aluminium is a corrosion-resistant metal
6.
What is a displacement reaction? Explain the statement Zinc can
solution, but copper cannot displace zinc from its salt solution
2 Write word equations and chemical equations for the following.
a. Reaction of sodium metal with atmospheric oxygen
b. Burning of sulphur in air
c. Dissolution of carbon dioxide in water
with hydrochloric acid​

Answer 1

Explanation:

rusting is the reason thas why iron become weak

Answer 2

Answer:

4.

• Corrosion is process in which metal reacts with substance present in the atmosphere to form surface compounds.
• When iron objects exposed to oxygen and moisture for a long period of time, the oxygen combines with the metal forming rust which weakens the iron objects

5.

a. Copper turns green because of chemical reactions with the elements. Copper when exposed to the elements undergoes a series of chemical reactions that give the shiny metal a pale green outer layer

b. The silver article becomes black after sometimes when exposed to air because silver reacts with sulphur which is present in the atmosphere and then forms silver sulphide. Thus the layer of this silver sulphide is formed on the surface of the silver article so they appear as dull or black.

c. The corrosion resistance of aluminum is because it forms a compact oxide layer over the surface. The oxide formed prevents aluminium from corrosion.

6.

• A reaction in which more reactive element displaces a less reactive element from the compound is called displacement reaction.
• Copper cannot displace zinc from its salt solution because the reactivity of zinc is higher than copper in the reactivity series. Only a metal which is higher reactive ( above the particular metal in the reactivity series ) can displace a metal of lower reactivity.

2.

a. Sodium + Oxygen ⇒ Sodium Oxide

      4 Na + O2 ⇒ 2 Na2O

b. Sulphur + Oxygen ⇒ Sulphur Dioxide

    S + O2  ⇒ SO2

c. Carbon dioxide + Water + Hydrochloric acid ⇒ Vinyl chloride + Oxygen

 4CO2 + 2H2O + 2HCl ⇒ 2C2H3Cl + 5O2

hope it helps you..