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By dissolving 5 g substance in 50 g of w...

By dissolving 5 g substance in 50 g of water, the decrease in freezing point is `1.2^(@)C` . The gram molal depression is `1.85^(@)C` . The molecular weight of substance is

A

`105.4`

B

`118.2`

C

`137.2`

D

`154.2`

Text Solution

Verified by Experts

The correct Answer is:
D
We know that, `m=(1000 K_(f)xx w)/(Delta TW)`
Here, `Delta T=1.2^(@)C, K_(f)=1.85^(@)`
`w=5g, W=50 g`
`m=(1000xx1.85xx5)/(1.2xx50)=154.2`.
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