Atomic Structure MCQs for NEET — Chemistry Questions with Answers

(C) He $\underset{I.E}{\overset{I}{\to }}H{e}^{+}+e^{-}; H{e}^{+}\underset{I.E}{\overset{II}{\to }}H{e}^{2+}+e^{-}$

I(I.E)+II(I.E) = 79eV

II(I.E) = 13.6eV x Z² = 13.6x4eV = 54.4eV

I(I.E) = 79-54.4=24.6eV.

(D) Fe²⁺ has 1s²,2s²2p⁶,3s²3p⁶3d⁶

configuration with 4 unpaired electron.

(B)            Electron            Proton            Neutron        $\mathrm{\alpha }$-particle

    e            1 unit               1 unit             zero               2 units

    m          1/1837 unit        1 unit            1 unit            4 unit

   e/m           1837                1                  zero               1/2

(A) Mass of neutron = 1.675 x 10^-27kg

Mass of electron = 9.108 x 10^-31 kg.

(B) Size of the first orbit of Hydrogen = 5.29 x 10^-9m

Size of the second orbit of Helium = 5.29 x 10^-9 x 2² /2= 10.58 nm.

(b) Fe is 3d⁶, 4s²; Fe²⁺: 3d⁶

if n = 3 then l=3 is not possible.

Isotones are these in which number of neutrons are same.

In O^2- , number of electrons are 10 and number of neutrons are 8