JEE Main 2022 · 27 Jun · Shift 1 · Chemistry Q61

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ChemistrySingle correct+4 / -1Question 61 of 90

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

Assertion (A) : At 10°C, the density of a 5 M solution of KCl [atomic masses of K & Cl are 39 & 35.5 g mol $^{-1}$ respectively], is ' $x$ ' g ml $^{-1}$ . The solution is cooled to $-21$ °C. The molality of the solution will remain unchanged.

Reason (R) : The molality of a solution does not change with temperature as mass remains unaffected with temperature.

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

Both (A) and (R) are true and (R) is the correct explanation of (A).

Both (A) and (R) are true but (R) is not the correct explanation of (A).

(A) is true but (R) is false.

(A) is false but (R) is true.

Answer and worked solution

Official answer: A

Assertion is true: molality depends only on masses, which do not change on cooling.

Reason is true and is exactly why.

(A)

Topics:Concentration and solubility Concentration terms

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JEE Main 2022 · 27 Jun · Shift 1, Chemistry question 61