What is the chemical formula of carbonic acid?

The correct option is A

${\mathrm{H}}_2{\mathrm{CO}}_3$

Explanation for the correct option:

Option (A) ${\mathrm{H}}_2{\mathrm{CO}}_3$- It is the chemical formula of carbonic acid.

Explanation for the incorrect option:

Option (B) ${\mathrm{H}}_3{\mathrm{CO}}_2$- It is the chemical formula of acetic acid.

Option (C) ${\mathrm{HNO}}_3$- It is the chemical formula of nitric acid.

Option (D) ${\mathrm{HNO}}_2$- It is the chemical formula of nitrous acid.

Therefore, Option (A) i.e. ${\mathrm{H}}_2{\mathrm{CO}}_3$ is the correct answer.