In the extraction of copper from copper glance, blister copper is formed by the evolution of gas \(\underline{X}\). The shape of molecule of \(\underline{X}\) is

The difference between the radii of \(3^{\text {rd }}\) and \(2^{\text {nd }}\) orbit of H -atom is \(x\) \(\mathrm{pm}\). The difference between the radii of \(4^{\text {th }}\) and \(3^{\text {rd }}\) orbit of \(\mathrm{Li}^{2+}\) ion is \(y \mathrm{pm}. y: x\) is equal to

Which of the following methods is useful for producing semiconductor grade metals of high purity ?

Polymers that can be softened on heating and hardened on cooling are called

The molecular formula of potash alum is

The sequence of reagents required to convert aniline to benzene nitrile are

Given below are two statements.
Statement I: In the decomposition of potassium chlorate, Cl is reduced.
Statement II: Reaction of Na with \(\mathrm{O}_2\) to form \(\mathrm{Na}_2 \mathrm{O}\) is a redox reaction.
The correct answer is

(i) \(\mathrm{H}_3 \mathrm{PO}_4(a q) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{H}_2 \mathrm{PO}_4^{-}(a q)\)
(ii) \(\mathrm{H}_2 \mathrm{PO}_4^{-}(a q) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{HPO}_4^{2-}(a q)\)
(iii) \(\mathrm{HPO}_4^{2-}(a q) \rightleftharpoons \mathrm{H}^{+}(a q)+\mathrm{PO}_4^{3-}(a q)\)
The equilibrium constants for the above reactions at a certain temperature are \(K_1, K_2\) and \(K_3\) respectively. The equilibrium constant for the reaction \(\mathrm{H}_3 \mathrm{PO}_4(a q) \rightleftharpoons 3 \mathrm{H}^{+}(a q)+\mathrm{PO}_4^{3-}(a q)\) in terms of \(K_1, K_2\) and \(K_3\) is

There are 2 bags each containing 3 white and 5 black balls and 4 bags each containing 6 white and 4 black balls. If a ball drawn randomly from a bag is found to be black, then the probability that this ball is from the first set of bags is

A line has slope $\mathrm{m}$ and $\mathrm{y}$-intercept 4. The distance between the origin and the line is equal to

Observe the following molecules/ions.
\(\mathrm{NH}_4^{+}, \mathrm{NH}_3, \mathrm{BF}_3, \mathrm{OH}^{-}, \mathrm{CH}_3^{+}, \mathrm{H}^{+}, \mathrm{CO}, \mathrm{C}_2 \mathrm{H}_4\)
The number of Lewis bases in the above list is

The locus of the point on the curve \(y=\sin x\) where the tangent drawn at that point always passes through the point \((0, \pi)\) is

The heat liberated when \(1.89 \mathrm{~g}\) of benzoic acid is burnt in a bomb calorimeter at \(25^{\circ} \mathrm{C}\) increases the temperature of \(18.94 \mathrm{~kg}\) of water by \(0.632^{\circ} \mathrm{C}\). If the specific heat of water at \(25^{\circ} \mathrm{C}\) is \(0.998 \mathrm{cal} /\left(\mathrm{g}^{\circ} \mathrm{C}\right)\), then find the heat of combustion of benzoic acid.