The density of 1 M solution of a compound ' X ' is 1.25 ~g ~mL^ -1 . The correct option for the molality of solution is (Molar mass of compound X=85 ~g )

Correct answer: B. 0.858 ~m Relation between Molality ( m ), Molarity (M) and density (d) is m= 1000 M 1000 × d-M × M_ solute Msolute denotes molar mass of solute. m=(1000 × 1)/((1000 × 1.25)-(1 × 85))=(1000)/(1250-85)=(1000)/(1165) m=0.858 m

NEET 2023

Exam: NEET
Year: 2023
Subject: Chemistry
Chapter: Some Basic Concepts of Chemistry

NEET 2023 · Chemistry · Some Basic Concepts of Chemistry

The density of 1 M solution of a compound ' X ' is 1.25 ~g ~mL^ -1...

The density of

1 \mathrm{M}

solution of a compound '

X

' is

1.25 \mathrm{~g} \mathrm{~mL}^{-1}

. The correct option for the molality of solution is (Molar mass of compound

X=85 \mathrm{~g}

)

Options

A $1.165 \mathrm{~m}$
B $0.858 \mathrm{~m}$
C $0.705 \mathrm{~m}$
D $1.208 \mathrm{~m}$

Correct answer

B. $0.858 \mathrm{~m}$

Step-by-step solution

Relation between Molality (

m

), Molarity (M) and density (d) is

m=\frac{1000 M}{1000 \times d-M \times M_{\text{solute }}}

Msolute denotes molar mass of solute.

m=\frac{1000 \times 1}{(1000 \times 1.25)-(1 \times 85)}=\frac{1000}{1250-85}=\frac{1000}{1165} \mathrm{m}=0.858

\mathrm{ m}

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