In the fluorite structure, the coordination number of Ca²⁺ ion is :

When electrons are trapped into the crystalline anion vacancy, the defect is known as:

With which one of the following elements  should silicon be doped so as to give p - type of semiconductor? 

Pressure remaining the same, the volume of a given mass of an ideal gas increases for every degree centigrade rise in temperature by definite fraction of its volume at:

If a gas expands at constant temperature, it indicates that:

In a closed flask of 5 L, 1.0 g of H₂ is heated from 300 to 600 K.  Which statement is not correct?

Which on of the following statements is  wrong for gases? 

The appearance of colour in solid alkali metal halides is generally due to:

The beans are cooked earlier in pressure cooker because:

A pure crystalline substance on being heated gradually first forms a turbid liquid at constant temperature, and still at higher temperature  turbidity completely disappears.  This behaviour is a characteristic of substances forming: