Number of $$\sigma$$ and $$\pi$$ bonds present in ethylene molecule is respectively :

The correct statement/s about Hydrogen bonding is/are

A. Hydrogen bonding exists when H is covalently bonded to the highly electro negative atom.

B. Intermolecular H bonding is present in $$o$$-nitro phenol

C. Intramolecular $$\mathrm{H}$$ bonding is present in HF.

D. The magnitude of $$\mathrm{H}$$ bonding depends on the physical state of the compound.

E. H-bonding has powerful effect on the structure and properties of compounds

Choose the correct answer from the options given below:

The number of species from the following that have pyramidal geometry around the central atom is _________

$$\mathrm{S}_2 \mathrm{O}_3^{2-}, \mathrm{SO}_4^{2-}, \mathrm{SO}_3^{2-}, \mathrm{S}_2 \mathrm{O}_7^{2-}$$

Number of molecules/ions from the following in which the central atom is involved in $$\mathrm{sp}^3$$ hybridization is ________.

$$\mathrm{NO}_3^{-}, \mathrm{BCl}_3, \mathrm{ClO}_2^{-}, \mathrm{ClO}_3^{-}$$