Answer any three of the following questions.
a) 31 g of an unknown molecular material is dissolved in 500 g of water. The resulting solution freezes at `271.14` K. Calculate the molar mass of the material. Given : `K_t` for water `=1.86"KK gmol1" T_(t)^(@)` of water `=273K`.

Explanation

`M_(0) = (k_(f) xx w_(a) xx 1000)/( Delta T_(r) xx w_(A) )`
i.e., `Delta T_(f) = T_(f)^(0) -T_(f) = 273- 271.13=85K`
`M_B = (K_(f) xx w_(a) xx 1000)/( Delta T_(f) xx w_(a) )`
`M_(B) = (1.86 xx 31 xx 1000)/( 1.86 xx 500)`
`M_(B) = 62 "g mol"^(-1)`