Q. .No. of valence electrons present in 4.2g of nitride ion (N^(3- are:
(a) 2.4times N
(b) 4.2times N
(c) 1.6times N
(d) 3.2times N ​

if na is Avogadros number then number of vaclence electron in 4.2 g of nitride ions (N3-is.2.4Na. so the answer is 2.4 na

Explanation:

Mass N3- ion = 14 g/mol. So,

4.2 g X (1 mol/14 g) = 0.3 mol N3-

Number of N3- ions = 0.3 mol X 6.02 X 10^23 ions/mol = 1.8 X 10^23 ions

Each N3- ion has 8 valence electrons, so total number of valence electrons = 1.8 X 10^23 X 8 = 1.4 X 10^24 valence electrons.

hope it helps

the formula would be mgso4

mgso[subscript]4

i think its 100.

hope this !