$$0.5 \mathrm{~g}$$ of an organic compound $$(\mathrm{X})$$ with $$60 \%$$ carbon will produce __________ $$\times 10^{-1} \mathrm{~g}$$ of $$\mathrm{CO}_{2}$$ on complete combustion.

The number of following statement/s which is/are incorrect is ___________

(A) Line emission spectra are used to study the electronic structure

(B) The emission spectra of atoms in the gas phase show a continuous spread of wavelength from red to violet

(C) An absorption spectrum is like the photographic negative of an emission spectrum

(D) The element helium was discovered in the sun by spectroscopic method

$$\mathrm{XeF}_{4}$$ reacts with $$\mathrm{SbF}_{5}$$ to form

$$[\mathrm{XeF}_{m}]^{\mathrm{n}+}\left[\mathrm{SbF}_{y}\right]^{z-}$$.

$$\mathrm{m}+\mathrm{n}+\mathrm{y}+\mathrm{z}=$$ __________

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