Ncert Exercises & Solutions

Taking the Bohr radius as $a_{0} = 53 pm$ , the radius of Li⁺⁺ ion in its ground state, on the basis of Bohr's model, will be about:

1. 53 pm

2. 27 pm

3. 18 pm

4. 13 pm

(c) Hint: The atomic radius depends on the atomic no.

Step 1: Compare the atomic no. of Lithium and Li⁺⁺.

The atomic number of lithium is 3, therefore, the radius of Li⁺⁺ ion in its ground state, on the basis of Bohr's model, will be about

\frac{1}{3}

times to that of Bohr radius.

Step 2: Find the atomic radius of Li⁺⁺.

Therefore, the radius of lithium-ion is near

\frac{55}{3} \approx 18 pm