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A certain substance A tetramerizes in wa...

A certain substance `A` tetramerizes in water to the extent of `80%`. A solution of `2.5 g` of `A` in `100 g` of water lowers the freezing point by `0.3^(@)C`. The molar mass of `A` is
a.`120` , b.`61` ,c.`60` ,d.`62`

A

122

B

31

C

244

D

62

Text Solution

Verified by Experts

The correct Answer is:
D
`alpha = (1-i)/(1-(1)/(n))`
`0.8 = (1-i)/(1-(1)/(n))i = 0.4`
`DeltaT = iK_(f) xx m`
`0.3 xx 0.4 xx 1.86 xx (w_(B) xx 1000)/(m_(a) xx w_(A))`
`0.3 xx 0.4 xx 1.86 xx (2.5 xx 1000)/(m_(a) xx 100)`
`m_(a) = 62`
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