Compound (X) undergoes following sequence of reactions to give the Lactone (Y).

In the depression of freezing point experiment

A. Vapour pressure of the solution is less than that of pure solvent

B. Vapour pressure of the solution is more than that of pure solvent

C. Only solute molecules solidify at the freezing point

D. Only solvent molecules solidify at the freezing point

Choose the most appropriate answer from the options given below :

Order of Covalent bond;

$$\mathrm{A.~KF > KI ; LiF > KF}$$

$$\mathrm{B.~KF < KI ; LiF > KF}$$

$$\mathrm{C.~SnCl_4 > SnCl_2 ; CuCl > NaCl}$$

$$\mathrm{D.~LiF > KF ; CuCl < NaCl}$$

$$\mathrm{E.~KF < KI ; CuCl > NaCl}$$

Choose the correct answer from the options given below :

It is observed that characteristic X-ray spectra of elements show regularity. When frequency to the power "n" i.e. $${v^n}$$ of X-rays emitted is plotted against atomic number "Z", following graph is obtained.

The value of 'n' is :