Given below are two statements : Statement (I) : Potassium hydrogen phthalate is a primary standard for standardisation of sodium hydroxide solution. Statement (II) : In this titration phenolphthalein can be used as indicator. In the light of the above statements, choose the most appropriate answer from the options given below :

Both Statement I and Statement II are correct

Statement I is incorrect but Statement II is correct

Both Statement I and Statement II are incorrect

Statement I is correct but Statement II is incorrect

Practical Organic Chemistry PYQ — JEE Main 2024 · 1 Feb · Shift 1 · Q6 with Solution

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Correct answer: A

Check Statement (I):

Potassium hydrogen phthalate (KHP) is a primary standard because it is:
- highly pure,
- stable in air,
- non-hygroscopic,
- has high molar mass,
- soluble in water.
Hence, it is commonly used to standardise sodium hydroxide solution.

The reaction is: $\mathrm{KHC_8H_4O_4 + NaOH \rightarrow KNaC_8H_4O_4 + H_2O}$

So, Statement (I) is correct.
Check Statement (II):

In the titration of KHP (a weak monoprotic acid) with NaOH (a strong base), the equivalence point lies in the basic range.

Phenolphthalein changes colour in the range about $8.2$ to $10.0$ , which is suitable for such titrations.

Therefore, phenolphthalein can be used as the indicator.

So, Statement (II) is correct.
Conclusion:

Both statements are correct.

Therefore, the correct option is: $\boxed{\text{A}}$
Comparison with stored answer:

Stored correct answer = A.

My derived answer also = A. Hence, they agree.

View written solutionFree

Correct answer: A

Check Statement (I):

Potassium hydrogen phthalate (KHP) is a primary standard because it is:
- highly pure,
- stable in air,
- non-hygroscopic,
- has high molar mass,
- soluble in water.
Hence, it is commonly used to standardise sodium hydroxide solution.

The reaction is: $\mathrm{KHC_8H_4O_4 + NaOH \rightarrow KNaC_8H_4O_4 + H_2O}$

So, Statement (I) is correct.
Check Statement (II):

In the titration of KHP (a weak monoprotic acid) with NaOH (a strong base), the equivalence point lies in the basic range.

Phenolphthalein changes colour in the range about $8.2$ to $10.0$ , which is suitable for such titrations.

Therefore, phenolphthalein can be used as the indicator.

So, Statement (II) is correct.
Conclusion:

Both statements are correct.

Therefore, the correct option is: $\boxed{\text{A}}$
Comparison with stored answer:

Stored correct answer = A.

My derived answer also = A. Hence, they agree.