The vapour pressure of water at `20^(@)C is 17.54mm`. When 20g of non - ionic substance is dissolved in 100g of water, the vapour pressure is lowered

Question

The vapour pressure of water at `20^(@)C is 17.54mm`. When 20g of non - ionic substance is dissolved in 100g of water, the vapour pressure is lowered

The vapour pressure of water at `20^(@)C is 17.54mm`. When 20g of non - ionic substance is dissolved in 100g of water, the vapour pressure is lowered by `0.30mm`. What is the molecular mass of the substance ?
A. `200.8`
B. `206.88`
C. `210.5`
D. `215.2`

Monjur Alahi

5 views

2025-01-04 04:42

1 Answers

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Salim Ahmed Kawsar · Accepted Answer · 2023-02-05T15:29:48+06:00

Salim Ahmed Kawsar

Correct Answer - B
Relative lowering in vapour pressure,
`(p^(@)-p_s)/(p^(@))=(x_(2))/(x_(2)+x_(1))=(w//m)/(w/m+W/M)`
`(0.30mm)/(17.54mm)=(20//m)/(20//m+100//18)`
`rArrm=206.88`

5 views Answered 2023-02-05 15:29