Both PH₃ and NH₃ are Lewis bases, but basic strength of PH₃  is less than that of NH₃ Explain. 'N' atom of NH₃ Explain 

'N' atom of NH₃ or PH₃ has a lone pair of electrons available for donation. Hence NH₃ and 
NH₃ and PH₃ are Lewis bases. The electron pair density on a larger 'p' atom is less than that on smaller 'N'' atom. Hence PH₃ is a weaker base.