What is the molecular formula of sulphurous acid?

Acid + Metal oxide $\longrightarrow$ ?

Pratyush took sulphur powder on a spatula and heated it. He collected the gas evolved by inverting a test tube over it,as shown in the figure below.
$(a)$ What will be the action of the gas on
$(i)$ dry litmus paper?
$(ii)$ moist litmus paper?
$(b)$ Write a balanced chemical equation for the reaction taking place.

What conversion occurs in the formation of milk into curd?

Which of the following substances enters our body when a red ant bites us?

Which of the following contains oxalic acid?