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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3si197

Which statements about estimation of elements by the Carius method are correct?

ASulphur is oxidised to sulphuric acid and weighed as $BaSO X_{4}$ .
BChlorine, bromine and iodine are weighed as the corresponding silver halides.
CFluorine in a fluoroalkane is estimated by weighing $AgF$ .
DPhosphorus is converted to phosphoric acid, precipitated as $MgNH X_{4} PO X_{4}$ and weighed as $Mg X_{2} P X_{2} O X_{7}$ .

Answer: A, B, D

In the sealed tube, fuming

HNO X_{3}

converts S to

H X_{2} SO X_{4}

(weighed as

BaSO X_{4}

), halogens to

HX

(precipitated as

AgX

) and P to

H X_{3} PO X_{4}

(precipitated as

MgNH X_{4} PO X_{4}

, ignited to

Mg X_{2} P X_{2} O X_{7}

).

AgF

is soluble in water, so fluorine cannot be estimated as AgF.

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