The wavelength of spectral line obtained in the spectrum of $\mathrm{Li}^{2+}$ ion, when the transition takes place between two levels whose sum is 4 and difference is 2 , is

Two liquids A and B form an ideal solution at temperature T K . At T K , the vapour pressures of pure A and B are 55 and $15 \mathrm{kN} \mathrm{m}^{-2}$ respectively. What is the mole fraction of A in solution of A and B in equilibrium with a vapour in which the mole fraction of A is 0.8?

$$ \text { From the following, how many compounds contain at least one secondary alcohol?} $$

Choose the correct answer from the options given below :

Given below are two statements :

Statement I : The dipole moment of R-CN is greater than R-NC and R-NC can

Statement II : R-CN hydrolyses under acidic medium to produce a compound which on treatment with $\mathrm{SOCl}_2$, followed by the addition of $\mathrm{NH}_3$ gives another compound $(\mathrm{x})$. This compound $(\mathrm{x})$ on treatment with $\mathrm{NaOCl} / \mathrm{NaOH}$ gives a product, that on treatment with $\mathrm{CHCl}_3 / \mathrm{KOH} / \Delta$ produces R-NC

In the light of the above statements, choose the correct answer from the options given below