`1.8 g` hydrogen atoms are excited to radiation .The study of spectra indicate that `27%` of the atom are in third energy level and `15 %` of atom in second energy level and the rest in ground state. IP of H is `13.6 eV`. Calculate
a. Number of atom present in first and third energy levels
b. Total energy envolved when all the atom return to the ground state

Explanation

To solve the problem, we will follow these steps:

### Step 1: Calculate the number of hydrogen atoms in 1.8 g
We know that 1 gram of hydrogen contains Avogadro's number of atoms, which is \(6.022 \times 10^{23}\) atoms.

\[ \text{Number of atoms in 1.8 g} = 1.8 \, \text{g} \times 6.022 \times 10^{23} \, \text{atoms/g} \]
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