Question

1 Give reason
(i) H2O is liquid at room temp. but H2S is a gas. Why
(ii) He2 does not exist but He2^+t exist. Why
(iii) Dipole moment of NH3 is greater the NF3​

Answer 1

Answer:

I) H2O is liquid because of its ability to form hydrogen bonds which is possible only in case of F , O and N because of their high electronegativity. While in case of H2S there is no hydrogen bond formation . Hence H20 is liquid while H2S is gas .

ii) According to valence bond theory,halfilled atomic orbitals can overlapp to form a bond. Thus two hydrogen atoms along with halffilled 1s orbital,overlapp with each other to form H₂ molecule. ... Filled orbital can not overlapp and hence cannot form a bond. Hence diatomic helium i.e.He₂ molecule does not exist

iii) in case of NH3, nitrogen is more electronegative than hydrogen,so it tries to pull the electrons from hydrogen atoms. where as in case of NF3, fluorine being more electronegative than nitrogen tries to pull the electrons from nitrogen opposite from that of nitrogen

Explanation:

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