(a, c, d)

Nitrogen is more electronegative than phosphorus.

So, dipole moment of trimethylamine is greater than trimethy phosphine.

In trisilyl ether the lone pair of electron on oxygen atom is less easily available for donation because of p -d delocalisation due to presence of the vacant d-orbital with Si. This however is not possible with carbon in CH3– O – CH3 due to the absence of d-orbital making it more basic.

Bond order of C2 and O2 are same i.e., 2. In C2 molecules both bonds are p-bonds whereas, there is one s and one -bond in O2 molecule

C2 = 131 pm ; O2 = 121 pm.