Explain the following:
(a) Oxygen molecule has formula `O_2` while sulfur has `S_g`.
(b) `CIF_3` exists whereas `FCl_3` does not.

CIF_3 exists but FCl_3 does not exist. Why?

Give one reason to explain why ClF_(3) exists but FCl_(3) does not exist?

Explain the formation of following molecules : PCl_3 ,CH_4 ,H_2 O , PH_3 , OF_2 , C_2 H_6

Explain the following : (i). FeCl_3 and FeBr_3 are well known, but FeI_3 has doubtful existence. (ii). Anhydrous FeCl_3 cannot be obtained by heating hydrated ferric chloride.

A molecule of H_(2) exist while that of the He_(2) does not. Explain.

On the basis of hydrogen bonding explain the following : (i) H_(2)O is a liquid at room temperature while H_(2)S is a gas (ii) Boiling point of NH_(3) is more than that of PH_(3)

What is catenation ? Explain why oxygen is diatomic, while sulfur is octa-atomic, S_g .

Iron oxide has formula Fe_"0.94"O. What fraction of Fe exists as Fe^(+3) ?

Explain the following situations : (i) In the structure of HNO_(3) molecule , the N-O bond (121 pm) is shorter than N-OH bond (140pm). (ii) SF_(4) is easily hydrolysed whereas SF_(6) is not easily hydrolysed. (iii) XeF_(2) has a straight linear structure and not a bent angular structure.

(a) Why elemental phosphorous does not exist as P_2 like N_2 ? (b) NCl_3 gets easily hydrolysed, while NF_3 does not. Why ?