Question

Q2. State a Chemical Reaction which is characterized by

a. Evolution of a gas

b. Change of colour

c. Formation of ppt.

d. Change of smell

e. Change of state​

Answer 1

Answer:

1.Evolution of gas:

The chemical reaction between zinc and dilute sulphuric acid is characterized by the evolution of hydrogen gas.

Zn(s) + H2SO4(aq) -------->ZnSO4(aq) + H2(g)

2.Change in colour:

Reaction between lead nitrate solution and potassium iodide solution.

Pb(NO3)2(aq) +2KI -------> PbI2(s) + 2KNO3(aq)

In this reaction colour changes from colourless to yellow.

3.Formation of precipitate:

Action of Barium Chloride on sodium sulphate.

BaCl2 (aq) + Na2SO4 (aq) ------> BaSO4(s)+2NaCl(aq)

4.Change in temperature change in temperature:

Action of dilute sulphuric acid on zinc

Zn(s) + H2SO4(aq) -------->ZnSO4(aq) + H2(g)

In this reaction heat is evolved.

5.Change in state:

When wax is burnt in the form of wax candle then Water and carbon dioxide are formed. Wax is a solid water is a liquid whereas carbon dioxide gas.

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