Chemistry NCERT Exemplar Solutions Class 12th Chapter Two

The elevation in boiling point for 1 molal solution of non-volatile solute A is 3K. The depression in freezing point for 2 molal solution of A in the same solvent is 6 K. The ratio of K_b and K_f i.e. K_b/K_f is 1 : X. The value of X is [nearest integer]

Consider an imaginary ion  The nucleus contains 'a'% more neutrons that the number f electrons in the ion. The value of 'a' is____________. [nearest integer]

Match List – I and List – II.

Choose the correct answer from the options given below

A gaseous mixture of two substances A and B, under a total pressure of 0.8 atm is in equilibrium with an ideal solution. The mole fraction of substance A is 0.5 in the vapour phase and 0.2 in the liquid phase. The vapour pressure of pure liquid A is_________atm. (Nearest integer)

If the wavelength for an electron emitted from H-atom is 3.3 * 10^-10m, then energy adsorbed by the electron in its ground state compared to minimum energy required for its escape from the atom, is ___________times. (Nearest integer)

[Given: h = 6.626 * 10^-34 Js]

Mass of electron = 9.1 * 10^-31 kg

At $300\mathrm{K}$ , the vapour pressure of a solution containing 1 mole of $n$ -hexane and 3 moles of $\mathrm{n}$ -heptane is $550\mathrm{m}\mathrm{m}$ of $\mathrm{H}\mathrm{g}$ . At the same temperature, if one more mole of $\mathrm{n}$ -heptane is added to this solution, the vapour pressure of the solution increases by $10\mathrm{m}\mathrm{m}$ of $\mathrm{H}\mathrm{g}$ . What is the vapour pressure in $\mathrm{m}\mathrm{m}\mathrm{H}\mathrm{g}$ of $n$ -heptane in its pure state ?

The region in the electromagnetic spectrum where the Balmer series lines appear is:

The vapour pressure of two volatile liquid A and B at 25°C are 50 Torr and 100 Torr, respectively. If the liquid mixture contains 0.3 mole fraction of A, then the mole fraction of liquid B in the vapour phase is $\frac{x}{17}.$  The value of x is____________.

If the work function of a metal is 6.63 * 10^-19J, the maximum wavelength of the photon required to remove a photoelectron from the metal is _______nm. (Nearest integer)

[Given h = 6.63 * 10^-34 Js, and c = 3 * 10⁸ ms^-1]

If O₂ gas is bubbled  through water at 303 K, the number of millimoles of O₂ gas that dissolve in 1 litre of water is______________. (Nearest integer)

(Given: Henry's Law constant for O₂ at 303 K is 46.82 k bar and partial pressure of O₂ = 0.920 bar)

(Assume solubility of O₂ in water in too small, nearly negligible)