Consider two reactions:
$(I) \, Zn + \text{conc. } HNO_3 \text{ (hot)} \to Zn(NO_3)_2 + X + H_2O$
$(II) \, Zn + \text{dil. } HNO_3 \text{ (cold)} \to Zn(NO_3)_2 + Y + H_2O$
Compound $X$ and $Y$ are respectively:

Which of the following elements does not form stable diatomic molecules?

Which of the following reaction products are represented correctly?
$(a)\ P_4 + 3NaOH(dil) + 3H_2O \to PH_3 + 3NaH_2PO_2$
$(b)\ 3Br_2 + 6NaOH(conc) \to 5NaBr + NaBrO_3 + 3H_2O$
$(c)\ NCl_3 + 3H_2O \to NH_3 + 3HOCl$
$(d)\ I_2 + 2NaOH \to NaI + NaOI + H_2O$
$(e)\ Al_4C_3 + 12H_2O \to 4Al(OH)_3 + 3CH_4$
$(f)\ N_2O_4 + H_2O \to HNO_3 + HNO_2$
$(g)\ NH_4NO_3 + NaOH \to NH_3 + NaNO_3 + H_2O$
Correct options are:

What happens when $H_{3}PO_{3}$ is heated?

With which of the following does $FeSO_4$ form a brown ring?

Which of the following does not produce ammonia upon heating?