In qualitative analysis of cation of second group, H2 S gas is passed in presence of HCl, sulphide ions obtained is sufficient for the precipitation of second group cations in form of their sulphides due to lower value of their solubility product (Ksp). Hence, fourth group cations are not precipitated because they require for exceeding their ionic product to their solubility products and higher sulphide ions concentration due to their higher Ksp which is not obtained here due to common ion effect. common ion Caution HCl is added before H2 S gas during qualitative analysis of second group radicals because the concentration of sulphide ions is suppressed by HCl due to common ion effect. The already present H+ions suppress the dissociation of H2 S by moving the reaction in the backward reaction.
H_2 ~S gas when passed through a solution of cations containing HCl precipitates the cations of second group of qualitative analysis but not those…
NEET UG 2005 — Chemistry Physical Chemistry
H2 S gas when passed through a solution of cations containing HCl precipitates the cations of second group of qualitative analysis but not those belonging to the fourth group. It is because
Held on 30 Apr 2005 · Verified 9 Jul 2026.
Options
- A
presence of HCl decreases the sulphide ion concentration
- B
solubility product of group II sulphides is more than that of group IV sulphides
- C
presence of HCl increases the sulphide ion concentration
- D
sulphide of group IV cations are unstable in HCl
Did you get this right?
Sign in to track your attempts and accuracy.
Your note
Sign in to keep a private note on this question. Nothing you write is ever public.
NEET UG Physical Chemistry in other years
More NEET UG Physical Chemistry questions
For the reaction 2SO₂(g) + O₂(g) ⇌ 2SO₃(g), ΔH = -198 kJ. Which condition favours forward reaction?
The unit of rate constant for a first-order reaction is:
Among the following choose the ones with equal number of atoms. A. 212 g of $\mathrm{Na}_2 \mathrm{CO}_3(\mathrm{~s})$ [molar mass $=106 \mathrm{~g}$ ] B. 248 g of $\mathrm{Na}_2 \mathrm{O}$ (s) [molar mass $=62 \mathrm{~g}$ ] C. 240 g of $\mathrm{NaOH}(\mathrm{s})$ [molar mass $=40 \mathrm{~g}]$ D. 12 g of $\mathrm{H}_2(\mathrm{~g})$ [molar mass $=2 \mathrm{~g}$ ] E. 220 q of $\mathrm{CO}_2(\mathrm{q})$ [molar mass $\left.=44 \mathrm{~g}\right]$ Choose the correct answer from the options given below:
For the reaction $\mathrm{A}(\mathrm{g}) \rightleftharpoons 2 \mathrm{~B}(\mathrm{~g})$, the backward reaction rate constant is higher than the forward reaction rate constant by a factor of 2500 , at 1000 K . [Given : $\mathrm{R}=0.0831 \mathrm{~L} \mathrm{~atm} \mathrm{~mol}^{-1} \mathrm{~K}^{-1}$ ] $\mathrm{K}_{\mathrm{p}}$ for the reaction at 1000 K is
The standard heat of formation, in $\mathrm{kcal} / \mathrm{mol}^{\text {of }} \mathrm{Ba}^{2+}$ is : [Given : standard heat of formation of $\mathrm{SO}_4^{2-}$ ion (aq) $=-216 \mathrm{kcal} / \mathrm{mol}$, Standard heat of crystallisation of $\mathrm{BaSO}_4(\mathrm{~s})=-4.5 \mathrm{kcal} / \mathrm{mol}$, standard heat of formation of $\left.\mathrm{BaSO}_4(\mathrm{~s})=-349 \mathrm{kcal} / \mathrm{mol}\right]$
Other Chemistry topics for NEET UG
Keep practicing Physical Chemistry
Work through every NEET UG Physical Chemistry PYQ, year by year.