Write a balanced chemical equation for the following: The reaction of carbon powder and concentrated nitric acid.

Carbon gets oxidised when it reacts with concentrated nitric acid and liberates reddish-brown fumes of nitrogen dioxide. The balanced chemical reaction is as follows: C + 4 HNO 3 → CO 2 + 4 NO 2 + 2 H 2 O

State one relevant reason for the following: Concentrated nitric acid appears yellow when it is left for a while in a glass bottle.

Concentrated nitric acid is a colourless liquid but is thermally unstable. With a little heat the acid dissociates into reddish-brown nitrogen dioxide gas that dissolves in the acid and turns the acid yellow.

A substance when dissolve in water gives hydrogen ion H + on dissociation is called an acid. It can also be defined as the substance that donate protons to the another substance. They are sour in the taste and turns blue litmus to red. The acids obtained from plants or animals are called organic acids. Examples: Citric acid, tartaric acid, etc. The acids obtained from minerals are called mineral acids or inorganic acids. Examples: Sulphuric acid, hydrochloric acid, etc.

Choose from the following list of substances, the one substance, that matches the description given below: Sulphur dioxide Chlorine Hydrogen sulphide Methane Sodium hydrogen sulphate Methanol The gas turns moist lead acetate paper black.

H 2 S turns moist lead acetate paper black. The black colour is due to the formation of lead sulphide. Hydrogen sulphide is a flammable, colourless gas with a characteristic odour of rotten eggs. Hydrogen sulphide is a weak acid and lead acetate is basic in nature. This is a simple acid-base reaction. H 2 S + ( CH 3 COO ) 2 Pb → PbS + 2 CH 3 COOH Black