Alloys are used for electrical heating devices rather than pure metals. Give reasons.

Why Biryani is costlier than plain rice ? Give reasons.

Explain the following. (a) Why is the tungsten used almost exclusively for filament of electric lamps? (b) Why are the conductors of electric heating devices, such as bread-toasters and electric irons, made of an alloy rather than a pure metal? (c) Why is the series arrangement not used for domestic circuits? (d) How does the resistance of a wire vary with its area of cross-section? (e) Why are copper and aluminium wires usually employed for electricity transmission?

In the chemical reactions hydrogen is more reactive than deuterium. Give the reason.

Why doctors use distilled water for injections ? Give reasons.

Why are coils of electric toasters and electric irons made of an alloy rather than a pure metal?

Assertion: The vapour pressure of mixture of ethanol and water is greater than pure water. Reason: Ethanol & water form an azeotropic mixture.

A common metal widely used in electrical cables and kitchen ware is

The wall of left ventricle is thicker than the wall of the right ventricle? Give reason