When soap is scrubbed on a stain of curry on a white cloth,why does it become reddish-brown,and why does it turn yellow again when the cloth is washed with plenty of water?

Identify the correct representation of the reaction occurring during the chlor-alkali process.

What happens when $CO_{2}$ is passed through lime water in excess?

$A$ compound $X$ is a constituent of baking powder. It is used as an antacid. When $X$ is heated, it releases a gas $Y$ which, when passed through lime water, turns it milky, and a salt $Z$ is formed, which is the main constituent of washing powder. Identify $X, Y$, and $Z$. Write balanced chemical equations for the reactions involved.

Which chemical is added by farmers to neutralize the acidic soil?

Which enzyme becomes active in the stomach during a low $pH$ value?