Acid/Base MCQs

A: Correct because acids turn blue litmus red. B: Wrong because green is not the acid response. C: Wrong because black is not a litmus result. D: Wrong because white is not a litmus result.

A: Correct because the standard buffer relation is pH = pKa + log of conjugate-base concentration divided by weak-acid concentration. B: Incorrect because the logarithmic term has a plus sign in the standard form. C: Incorrect because adding 14 to pKa is not the buffer equation. D: Incorrect because multiplying concentrations does not directly give pH.

A: Correct because the concentration ratio is 1, log 1 is zero, so pH = pKa. B: Incorrect because a buffer is not necessarily neutral. C: Incorrect because 14 is not generally related to pKa equality. D: Incorrect because pH becomes zero only in very acidic conditions, not because the ratio is one.

A: Correct because a suitable indicator changes color near the equivalence region and signals the endpoint. B: Incorrect because boiling dry destroys the titration setup. C: Incorrect because mass alone does not identify the endpoint. D: Incorrect because a metal strip is not the standard endpoint detector.

A: Correct because the reacting acid and base are present in chemically equivalent stoichiometric amounts. B: Incorrect because boiling is unrelated to equivalence. C: Incorrect because adding indicator does not itself establish equivalence. D: Incorrect because a burette need not be emptied.

A: Correct because a burette has fine graduations and a stopcock for controlled delivery of variable volume. B: Incorrect because a beaker is not sufficiently accurate for titration delivery. C: Incorrect because a test tube is not calibrated for precise volume delivery. D: Incorrect because a watch glass is not a volumetric instrument.

A: Correct because a volumetric pipette is calibrated to deliver one fixed volume accurately. B: Incorrect because a measuring cylinder is less precise. C: Incorrect because an evaporating dish is used for heating and evaporation. D: Incorrect because a funnel assists transfer or filtration but does not measure a fixed accurate volume.

A: Correct because a conical flask allows swirling without excessive splashing. B: Incorrect because the burette holds titrant, not normally the analyte. C: Incorrect because a watch glass is unsuitable for titration mixing. D: Incorrect because a gas jar is intended for gases.

A: Correct because a standard solution has a precisely known concentration. B: Incorrect because standard solutions can have many colors. C: Incorrect because they may be acidic, basic, or neutral. D: Incorrect because their prepared volume need not always be one litre.

A: Correct because high purity, stability, and definite composition allow accurate preparation by direct weighing. B: Incorrect because volatility and impurity cause mass and composition errors. C: Incorrect because primary standards are commonly stable solids, not necessarily gases. D: Incorrect because rapid decomposition prevents accurate use.