Which of the following substances is an antacid?

Which of the following substances will not give carbon dioxide on treatment with dilute acid?

$(a)$ What is a universal indicator?
$(b)$ Write the chemical equation involved in the preparation of sodium hydroxide. Name the process.

You have two solutions $A$ and $B$. The $pH$ of solution $A$ is $6$ and the $pH$ of solution $B$ is $8$. Which solution has more hydrogen ion concentration? Which one of these is acidic and which one is basic?

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

$A$ metal $M$ forms an oxide with the formula $M_{2}O_{3}$. It dissolves in both dilute sulphuric acid and dilute sodium hydroxide solution. Identify the metal and write the chemical equations for the reactions involved.