a. molten NaCl

Explanation: Molten NaCl can conduct electricity because, in its liquid form, sodium chloride dissociates into ions that are free to move.

c. Deep blue

Explanation: When excess aqueous ammonia is added to an aqueous solution of copper sulfate, a deep blue solution is formed.

b. Brass

Explanation: Brass is an alloy that contains zinc. It is primarily composed of copper and zinc. Bell metal, bronze, and duralumin do not contain zinc in their composition.

d. C₂H₆

Explanation: C₂H₆ (ethane) is a saturated hydrocarbon, meaning it contains only single bonds between carbon atoms. The other compounds, C₃H₆ (propene), C₂H₄ (ethylene), and C₂H₂ (ethyne), are unsaturated hydrocarbons with double or triple bonds.

Domestic cooking and lighting in villages.

OR

NO (nitric oxide) acts as a catalyst in breaking down ozone (O₃) into oxygen (O₂) in the ozone layer, thereby contributing to ozone depletion.

Petrol.

Under constant pressure at -273ºC temperature the volume of an ideal gas will be 0 according to Charles’ law.

The unit of M is gram in the equation PV=W/M RT.

False

OR

Among iron, invar and copper invar has the least coefficient of linear expansion.

The angle of incidence will be greater when light travels from a rarer to a denser medium.

A Convex mirror is used in the viewfinder of a motor car.

Resistance decreases with the increase of temperature in the semiconductor.