MCQ
The Bohr orbit radius for the hydrogen atom $(n = 1)$ is approximately $0.530\,\mathop A\limits^o $. The radius for the first excited state $(n = 2)$ orbit is ........... $\mathop {\rm{A}}\limits^{\rm{o}} $
- A$0.13$
- B$1.06$
- C$4.77$
- ✓$2.12$
$r = {r_0} \times {2^2}$ $ = 0.53 \times 4$ $ = 2.12\,{\rm{{\mathop A\limits^o }}}$
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| Column $I$ | Column $II$ |
| $(A)$ $CH_3COONa$ | $(i)$ Almost neutral, $pH > 7$ or $< 7$ |
| $(B)$ $NH_4Cl$ | $(ii)$ Acidic, $pH < 7$ |
| $(C)$ $NaNO_3$ | $(iii)$ Alkaline, $pH > 7$ |
| $(D)$ $CH_3COONH_4$ | $(iv)$ Neutral, $pH = 7$ |