What is the frequency of a X-ray photon whose momentum is 1.1 x 10^-23 kg-ms^-2 ?

• 5 x 10¹⁶ Hz

• 0.5 x 10²⁷ Hz

• 0.5 x 10¹⁸ Hz

• 5 x 10¹⁸ Hz

The magnitude of orbital angular momentum of an electron of azimuthal quantum number 2 is :

• $\frac{2\mathrm{h}}{2\mathrm{\pi }}$

• $\frac{\sqrt{6}\mathrm{h}}{2\mathrm{\pi }}$

• $\frac{\sqrt{2}\mathrm{h}}{2\mathrm{\pi }}$

• $\frac{6\mathrm{h}}{2\mathrm{\pi }}$

The pH of a 0.02 M solution of HCl is :

• 2.2

• 2.0

• 0.3

• 1.7

The solubility product of Mg(OH)₂ at 25°C is 1.4 x 10^-11 .What is the solubility of Mg(OH)₂ in g/L ?

• 0.0047 g/L

• 0.047 g/L

• 0.0087 g/L

• 0.087 g/L

The heat of formarion of CO₂ is - 393 kJ mol^-1 .The amount of heat evolved in the formation of 0.156 kg of CO₂ .

• - 1393 kJ

• + 1165.5 kJ

• + 1275.9 kJ

• - 1165.5 kJ

The geometry of methane molecule is :

• tetrahedral

• pyramidal

• octahedral

• square planar

Heisenberg's uncertainty principle can be explained as :

• $∆$x $⩾$ $\frac{∆\mathrm{p} \times \mathrm{h}}{4\mathrm{\pi }}$

• $\mathrm{∆}$x x $∆$p $⩾$ $\frac{\mathrm{h}}{4\mathrm{\pi }}$

• $∆$x x $∆$p $⩾$ $\frac{\mathrm{h}}{\mathrm{\pi }}$

• $∆$p $⩾$ $\frac{\mathrm{\pi h}}{∆\mathrm{x}}$

8.

The bond energy is the energy required to :

• dissociate one mole of the substance

• dissociate bond in 1 kg of the substance

• break one mole of similar bonds

• break bonds in one mole of the substance

Heat of neutralisation of an acid with a base is 13. 7 kcal when :

• both acid and base are weak

• acid is weak and base is strong

• both acid and base are strong

• acid is strong and base is weak

Hess's law is based on :

• law of conservation of mass

• law of conservation of energy

• enthalpy is a state function

• none of the above