Question

the total number of electrons in 4.2g of N3- ion is(NA IS THE AVAGARDO NO.)
1)2.1 NA
2)4.2 NA
3)3NA
4)3.2NA

Answer 1

Nitrogen-Symbol-N -7(atomic number)
N³⁻ ion = 1s²2s²2p⁶
Total number of electrons =10
atomic mass of N=14
14g of N³⁻ ion contains 10NA electrons
where NA - Avagadro number
so, 1 g of N³⁻ ion =10NA/14
∴4.2g of N³⁻ ion =4.2x 10NA/14
=3NA

∴The total number of electrons in 4.2g of N3- ion 3NA ---- option (3)is correct

Answer 2

Answer:N3-   has 10 electrons

Therefore,

Mole = weight / atomic mass

         = 4.2 / 14

         = 0.3

No. Of mole = 0.3 × 10

                    = 3

Total no. Of electron = 3× Na

                                   = 3Na

Explanation: therefore, option(c) is correct...