Calculate van't Hoff factor of 0.2 m aquesous solution of an electrolyte if it freezes at $-$0.7 K $\left[\mathrm{K}_{\mathrm{f}}=1.86 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}\right]$

What is momentum of a microscopic particle having de Broglie's wavelength 6.0 A?

$$\left(\mathrm{h}=6.63 \times 10^{-34} \mathrm{Js}\right)$$

Which from following species acts as base ${ }^1$, according to Bronsted-Lowry theory?

$$\mathrm{HCl}+\mathrm{NH}_3 \text { 目的 } \mathrm{NH}_4^{+}+\mathrm{Cl}^{-} $$

Which of the following reactions represents Clemmensen reduction?