(a) Write happens when calcium reacts with water? Write the chemical equation of the reaction of calcium.
(b) Write the chemical equation of the reaction which takes place when iron reacts with dilute sulphuric acid. What happens when the gas produced is ignited with a burning matchstick?

(a) When calcium reacts with water, it forms calcium hydroxide and hydrogen gas. Due to the formation of hydrogen bubbles that stick to the surface of calcium, it starts floating on water.

$Ca\left(s\right)+2H_{2}O\left(l\right)⟶Ca\left(OH{)}_2\right(aq)+H_2(g)$

(b) The chemical equation of the reaction between iron and dilute sulphuric acid is as follows:

$Fe\left(s\right)+H_{2}S{O}_4\left(aq\right)⟶FeS{O}_4\left(aq\right)+H_2\left(g\right)$

When the hydrogen gas produced is ignited with a burning matchstick, the gas burns with a 'pop' sound and a small explosion takes place.