Question

In which of the following pairs of bonds is the shorter bond length not followed by the longer bond length?

C=O, C=S

C?Si, C?S

C?C, C=C

S?O, P?O

N?O, N=O

Answer 1

we know that

in the periodic table

when we move down the group , the atomic size increases

when we move from left to right in a period , the atomic size decreases

1)

given C=0 and C=S

0xygen and sulphur belong to the same group

and

sulphur is placed below oxygen

so

the atomic size of S is more than C

as a result

the bond length of C=S is more than that of C=0

2)

given C-Si and C-S

S is placed to the right of Si in the same period

so

the atomic size of Si is more than S

as a result

the bond length of C-Si is more than that of C-S

3)

given C-C and C=C

we know that

the bond length of singe bond > double bond > triple bond

so

the bond length of C-C is more than C=C

4)

given S-0 and P-0

S is place to the right of P in the same period

so

atomic size of P is more than S

as a result

the bond length of P-0 is more than S-0

5)

given N-0 and N=0

as double bond is shorter than single bond

the bond length of N-0 is more than N=0

so

the pairs of bonds is the shorter bond length not followed by the longer bond length are

2) C-Si , C-S

3) C-C , C=C

5) N-0 , N=0