Equilibrium practice · Mixed difficulty

Option A ($\mathrm{V}_2 \mathrm{O}_5$) is correct because Vanadium pentoxide ($\mathrm{V}_2 \mathrm{O}_5$) is the catalyst used in the Contact process for the production of $\mathrm{SO}_3$.

Option B (64) is correct because the equilibrium constant, Kc, is independent of volume changes for the given reaction.

Option A is correct because ammonium chloride ($NH_4Cl$) is a salt of a weak base ($NH_4OH$) and a strong acid (HCl), making it acidic due to the hydrolysis of the ammonium ion.

Option B (The solution is unsaturated) is correct because the Ionic Product (IP) is less than the solubility product (Ksp), indicating that more salt can dissolve in the solution.

Option A (12 mg) is correct because it calculates the mass of water vapor absorbed by SrCl2.2H2O(s) by considering the difference between the actual and equilibrium partial pressures of water vapor.

Option A (Weak acid) is correct because phenolphthalein is a weak organic acid that exists in equilibrium between its protonated and deprotonated forms.

Option A (If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion) is correct because the equilibrium constant is indeed affected only by temperature, and adding an inert gas at constant volume does not shift the equilibrium.

Option B (2.496) is correct because it is the number of moles of HI remaining at equilibrium after dissociation.

Option D ($9.3$) is correct because it is calculated using the Henderson-Hasselbalch equation for a basic buffer.

Option B (8.8) is correct because it's the calculated pH of the buffer solution formed after mixing the weak acid and strong base.

Option D (I, II, III and IV) is correct because both H+ and OH- can be hydrated, forming the given hydrated species.

Option D (250) is correct because it is calculated by substituting the equilibrium concentrations into the Kc expression.

Option A ($K=e^{-\Delta G^{\circ} / R T}$) is correct because it represents the correct relationship between the equilibrium constant (K) and the standard Gibbs free energy change (Δ G°).

Option B (8) is correct because, according to the Henderson-Hasselbalch equation, when the concentrations of the acid and its conjugate base are equal, the pH equals the pKa, which is 8 in this case.

Option C is correct because NH4Cl is a salt of a weak base and strong acid, resulting in an acidic solution with a pH less than 7.

Option B (Lewis base) is correct because amines have a lone pair of electrons on the nitrogen atom, making them electron-pair donors, which is the definition of a Lewis base.

Option A (If both the statements are TRUE and STATEMENT-2 is the correct explanation of STATEMENT-1) is correct because the reaction quotient is greater than Kp, causing the equilibrium to shift backward and increase the partial pressure of A.

Option A ($2.01 \times 10^{21}$ atoms) is correct because it represents the number of magnesium atoms calculated from the mass percentage in the given amount of chlorophyll.

Option B (12.6) is correct because after reacting 100 mL of 0.2 M HCl with 400 mL of 0.1 M NaOH, the pH of the resulting solution is 12.6.

Option D ($\mathrm{CaC}{\mathrm{l}_2}$) is correct because it is a salt formed from a strong acid (HCl) and a strong base (Ca(OH)₂), and therefore does not hydrolyze.

Option D is correct. Statement I is incorrect because diluting an acidic solution (pH 6) will increase the pH but it will not exceed 7. Statement II is correct because pH increases by one unit for every 10-fold decrease in [H+].

Option D (Nothing happens) is correct because adding an inert gas at constant volume does not shift the equilibrium.

Option D (Below $20.9 \%$) is correct because for CuSO4.5H2O to effloresce, the partial pressure of water vapor in the air must be less than that at equilibrium.

Option D (less than x / 2 M) is correct because adding water shifts the equilibrium to the left, decreasing the concentration of Cu2+ to less than half its original value.

Option D ($\mathrm{p}{K_\mathrm{a}} + \log 2$) is correct because adding more salt to the buffer changes the salt/acid ratio, affecting the pH as described by the Henderson-Hasselbalch equation.

Option C (${\log _{10}}\frac{{1}}{{{{K_a}}}}$) is correct because the $pK_a$ is defined as the negative logarithm (base 10) of the acid dissociation constant ($K_a$), which is equivalent to the logarithm of the reciprocal of $K_a$.

Option B is correct because both the assertion and the reason are true, but the reason is not a correct explanation of the assertion. The pH of a buffer changes with temperature due to changes in the equilibrium constants of the buffer components, and the ionic product of water also changes with temperature.

Option A ($4\times 10^{-14}$) is correct because the ionic product of water ($K_w$) increases with temperature, and at $50^{\circ} \mathrm{C}$, it is approximately $4\times 10^{-14}$.

Option A ($\mathrm{Na}_2 \mathrm{CO}_3$) is correct because it is a salt of a weak acid and a strong base, resulting in an alkaline solution due to hydrolysis.

The correct answer is A (9.26) because at the given concentrations, the pOH equals pKb, and pH equals pKa.