Question

Q-1--> What is observed when a solution of potassium iodide is added to a solution of lead nitrate is taken in a test tube?
(1) What type of reaction is this?
(2)Write a balanced chemical equation to represent the above reaction.
Q-2--> A brown substance 'X' on heating in air forms a substance 'Y'. When hydrogen gas is passed
heated 'Y', it again changes back into 'X'.
(i)Name the substance 'X' and 'Y'.
(ii) Name the type of chemical reactions occurring during both the changes.
(iii) Write the chemical equations of the reactions.​

Answer 1

Answer:

Q1 1) double displacement reaction

2)Pb(NO3)2+2Kl-----2KNO3+Pbl2

Q2

1) X=copper

Y=copper oxide

2) Oxidation and reduction reaction

3) 2Cu + O2------- 2CuO

CuO + H2------ Cu + H2O

Answer 2

Ans1 precipitation reaction takes place

yellow precipitate of lead iodide is formed along with potassium nitrate.

Pb(NO3)2+2Kl - Pbl2+2KNO3

ans2. The substance X is copper. On heating in air, it forms copper oxide Y.

When hydrogen gas is passed over black copper oxide then it turns brown as oxygen is removed by hydrogen.

first oxidation of x second reduction of y

2Cu+O2 - 2CuO

Cu0+H2 - Cu + H2O