NEET Practice Questions (MCQs) with Answers & Solutions

(A) The central part consisting whole of the positive  charge and most of the mass caused by nucleus, it extremely small in size compared to the size of the atom.

(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.