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NEET UG CHEMISTRY MCQ: PRACTICAL CHEMISTRY

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Analyzing +4 | -1

Given below are two statements one is labelled as Assertion (A) and the other is labeilled as Reason.

Assertion (A): In the titration of HCl against NaOH, phenolphthalein is used as suitable indicator.

Reason (R): Phenolphthalein is pink coloured in basic medium.

In the light of above statements, choose the most appropriate answer from the options given below.

View answer and explanation

Correct option: D

If both (A) and (R) are correct, but (R) is not the
correct explanation of (A)

Option D is correct because both the assertion and reason are correct, but the reason does not explain why phenolphthalein is a suitable indicator for the titration of HCl against NaOH.

More Questions from PRACTICAL CHEMISTRY

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A pale green crystalline inorganic salt (A) dissolves freely in water. It gives a brown precipitate on addition of aqueous

\mathrm{NaOH}.

The solution of (A) also gives a black precipitate on bubbling

\mathrm{H}_2 \mathrm{S}

in alkaline medium. An aqueous solution of the (A) decolorizes the pink colour of the permanganate solution. The metal in the salt solution is

100 \mathrm{~ml}

\mathrm{NaHC}_2 \mathrm{O}_4

50 \mathrm{~ml}

0.1 \mathrm{~M} \, \mathrm{KMnO}_4

solution in acidic medium. Volume of

0.1 \mathrm{~M} \mathrm{~NaOH}

100 \mathrm{~ml}

\mathrm{NaHC}_2 \mathrm{O}_4

is The ion that cannot be precipitated by both

{HCl}

{H}_2 {S}

is The rapid change of pH near the stoichiometric point of an acid-base titration in the basis of indicator detection. pH of the solution is related to ratio of the concentrations of the conjugated acid

(HIn)

(In)

forms of the indicator by the expression. On heating colourless solid

A,

B

(liquid at room temp.) and gas

C

A

is decomposed by

\mathrm{NaOH}

on heating to form gas

D

giving white fumes with

\mathrm{HCl}.

{C}

800 \mathrm{~ml} / \mathrm{g}

at N.T.P. Hence

A

HCl

solution is titrated to a pink phenolphthalein endpoint by adding a

\mathrm{NaOH}

solution while stirring. If a solution becomes pink throughout but loses its color upon standing for a short time, what should be done to restore the color?