H₂S 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: 

• presence of HCl decreases the sulphide ion concentration

• presence of HCl increases the sulphide ion concentration

• solubility product of group II sulphides is more than that of group IV sulphides

• sulphides of group IV cations are unstable in HCl

A + B $\rightleftharpoons$ C + D. If initially the concentration of A and B are both equal but at equilibrium, concentration of D will be twice of that of A, then what will be the equilibrium constant of reaction?

• 4/9

• 9/4

• 1/9

• 4

Given pH of a solutionA is 3 and it is mixed with another solution B having pH 2. If both mixed, then resultant pH of the solution will be :

• 3 : 2

• 1 : 9 

• 3 : 4

• 3 : 5

When NaNO₃ is heated in a closed vessel oxygen is liberated and NaNO₃ is left behind,

At equilibrium:

• addition of NaNO₂ favours reverse reaction

• addition of NaNO₃ favours reverse reaction

• increasing temperature favours forward reaction

• decreasing temperature favours backward reaction

${\mathrm{CaCO}}_{3 } \rightleftharpoons \mathrm{CaO} + {\mathrm{CO}}_2 \mathrm{reaction} \mathrm{in} \mathrm{lime} \mathrm{kiln} \mathrm{goes} \mathrm{to} \mathrm{completion} \mathrm{because}$:

• CaO does not react to CO₂  to give CaCO₃

• backward reaction is very low

• CO₂ formed escapes out

• None of the above

Consider the following reversible reaction at equilibrium:

${\text{2H}}_2\mathrm{O} \left(\mathrm{g}\right) \rightleftharpoons 2 {\mathrm{H}}_2\mathrm{O} \left(\mathrm{g}\right) + {\mathrm{O}}_2 \left(\mathrm{g}\right) ; \mathrm{\Delta H} = +24.7 \mathrm{KJ}$

The maximum decomposition of H₂O(g) will occur by which of the following change in conditions.

• Increasing temperature and decreasing pressure

• Decrease temperature and increasing pressure

• Increasing both temperature and pressure

• Increasing temperature at constant pressure

The pH of a 10^-10M - NaOH solution is

• 10

• 7.01

• 6.99

• 4

Which has minimum solubility?

• Bi₂S₃

• Ag₂S

• CoS

• PbS

NaOH(aq), HCl(aq), and NaCl(aq) concentration of each is 10^-3 M. Their pH will be respectively

• 10, 6, 2

• 11, 3, 7

• 10, 3, 7

• 10, 4, 7

On adding A to the reaction at equilibrium, AB (s) $\rightleftharpoons$ A(g) + B(g) the new equilibrium concentration of A becomes double, the equilibrium concentration of B would become:

• 1/2 of its original value

• 1/4 of its original value

• 1/8 of its original value

• Twice its original value