JEE CHEMISTRY MCQ: P-BLOCK ELEMENTS

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Assertion (A) : Both

\mathrm{H}_3 \mathrm{PO}_3

and

\mathrm{H}_3 \mathrm{PO}_4

have the same number of hydrogen atoms but

\mathrm{H}_3 \mathrm{PO}_4

is a tribasic acid and

\mathrm{H}_3 \mathrm{PO}_3

is a dibasic acid.

Reason (R) : 1 mole of

\mathrm{H}_3 \mathrm{PO}_3

is neutralised by 2 moles of

\mathrm{NaOH}

while 1 mole of

\mathrm{H}_3 \mathrm{PO}_4

is neutralised by 3 moles of

\mathrm{NaOH}

View answer and explanation

Correct option: B

Both

\mathbf{A}

and

\mathbf{R}

are true but

\mathbf{R}

is not the correct explanation of

\mathbf{A}

Option B (Both

\mathbf{A}

and

\mathbf{R}

are true but

\mathbf{R}

is not the correct explanation of

\mathbf{A}

) is correct because both the assertion and the reason are true statements, but the reason doesn't directly explain why

\mathrm{H}_3\mathrm{PO}_3

is dibasic and

\mathrm{H}_3\mathrm{PO}_4

is tribasic.

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