The titration curve of weak acid vs. strong base with phenolphthalein as indictor) is shown below. The $$\mathrm{K}_{\text {phenolphthalein }}=4 \times 10^{-10}$$.

Given: $$\log 2=0.3$$

The number of following statement/s which is/are correct about phenolphthalein is ___________

A. It can be used as an indicator for the titration of weak acid with weak base.

B. It begins to change colour at $$\mathrm{pH}=8.4$$

C. It is a weak organic base

D. It is colourless in acidic medium

When a $$60 \mathrm{~W}$$ electric heater is immersed in a gas for 100 s in a constant volume container with adiabatic walls, the temperature of the gas rises by $$5^{\circ} \mathrm{C}$$. The heat capacity of the given gas is ___________ $$\mathrm{J} \mathrm{K}^{-1}$$ (Nearest integer)

Molar mass of the hydrocarbon (X) which on ozonolysis consumes one mole of $$\mathrm{O}_{3}$$ per mole of $$(\mathrm{X})$$ and gives one mole each of ethanal and propanone is _________ $$\mathrm{g}~ \mathrm{mol}^{-1}$$

(Molar mass of $$\mathrm{C}: 12 \mathrm{~g} \mathrm{~mol}^{-1}, \mathrm{H}: 1 \mathrm{~g} \mathrm{~mol}^{-1}$$ )

The vapour pressure vs. temperature curve for a solution solvent system is shown below.

The boiling point of the solvent is __________ $${ }^{\circ} \mathrm{C}$$.