Electronegativity increases on moving left to right in a period and decreases for the period below it (∵n= increases) ∵(N and C) and (Si and P) respectively belongs to (n=2) and (n=3) ∴ Electronegativity of N> electronegativity of C and electronegativity of P> electronegativity of Si Hence, correct order is: Si<P<C<N