A compound 'X' is a weak acid and it exhibits colour change at pH close to the equivalence point during neutralization of NaOH with $$\mathrm{CH}_{3} \mathrm{COOH}$$. Compound 'X' exists in ionized form in basic medium. The compound 'X' is

'x' g of molecular oxygen $$\left(\mathrm{O}_{2}\right)$$ is mixed with $$200 \mathrm{~g}$$ of neon (Ne). The total pressure of the non-reactive mixture of $$\mathrm{O}_{2}$$ and Ne in the cylinder is 25 bar. The partial pressure of Ne is 20 bar at the same temperature and volume. The value of 'x' is _________.

[Given: Molar mass of $$\mathrm{O}_{2}=32 \mathrm{~g} \mathrm{~mol}^{-1}$$.

Molar mass of $$\mathrm{Ne}=20 \mathrm{~g} \mathrm{~mol}^{-1}$$]

Consider, $$\mathrm{PF}_{5}, \mathrm{BrF}_{5}, \mathrm{PCl}_{3}, \mathrm{SF}_{6},\left[\mathrm{ICl}_{4}\right]^{-}, \mathrm{ClF}_{3}$$ and $$\mathrm{IF}_{5}$$.

Amongst the above molecule(s)/ion(s), the number of molecule(s)/ion(s) having $$\mathrm{sp}^{3}\mathrm{~d}^{2}$$ hybridisation is __________.

$$1.80 \mathrm{~g}$$ of solute A was dissolved in $$62.5 \mathrm{~cm}^{3}$$ of ethanol and freezing point of the solution was found to be $$155.1 \mathrm{~K}$$. The molar mass of solute A is ________ g $$\mathrm{mol}^{-1}$$.

[Given : Freezing point of ethanol is 156.0 K.

Density of ethanol is 0.80 g cm^$$-$$3.

Freezing point depression constant of ethanol is 2.00 K kg mol^$$-$$1]