What dowe observe when-

a]dilutesulphuric acid is added to granulated zinc?

b]a few pieces of ironare dropped in a blue solution of copper sulphate?

c]solid lead nitrate is heated?

a] when dilute sulphuric acid is added to granulated zinc, we observe effervescence is evolved which is hydrogen gas, since dilute sulphuric acid reacts with zinc to form zinc sulphate and hydrogen.

b] when a few pieces of iron are dropped into a blue solution of copper sulphate, the solution turns green due to the formation of iron sulphate and there is a red deposit on the iron as copper settles on it.

c]when solid lead nitrate is heated, a reddish brown gas is evolved and a pale yellow liquid is left behind. This is because when solid lead nitrate is heated, it decomposes into lead oxide, nitrogen dioxide and oxygen.

Hope this helps!