If the approximate $pH$ of a solution is $7,$ what will be the colour of $pH$ paper when dipped into that solution?

$(a)$ Give the chemical names of acids present in:
$(i)$ ants
$(ii)$ lemon
$(iii)$ milk
$(iv)$ tomato

In a basic aqueous solution,if the concentration of $[OH^-]$ decreases,what happens to the $pH$?

$A$ 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.

$A$ sample of soil is mixed with water and allowed to settle. The clear supernatant solution turns the pH paper yellowish-orange. Which of the following would change the colour of this pH paper to greenish-blue?

Match the chemical substances given in Column $(A)$ with their appropriate application given in Column $(B)$.

Column $(A)$	Column $(B)$
$(A)$ Bleaching powder	$(i)$ Preparation of glass
$(B)$ Baking soda	$(ii)$ Production of $H_2$ and $Cl_2$
$(C)$ Washing soda	$(iii)$ Decolourisation
$(D)$ Sodium chloride	$(iv)$ Antacid