Which of the following contains oxalic acid?

Acids do not show acidic behaviour in the absence of water but do so in water. Justify this statement with the help of a chemical equation.

What is the unit of molar mass?

Name the gas evolved when dilute $HCl$ reacts with sodium hydrogen carbonate. How is it recognized?

Name the acid present in ant sting and give its chemical formula. Also,suggest a common method to get relief from the discomfort caused by the ant sting.

What is formed by the reaction of carbon dioxide with water?