Question

Potassium selenate is isomorphous with potassium sulphate and contains `50.0%` of `Se`. The atomic weight of `Se` is
a. `142`, b. `71`, c. `47.33`, d. `284`
A. 142
B. 71
C. 47.33
D. 284

Answer 1

Correct Answer - A
`K_2 SO_4` and `K_2 SeO_4` are isomorphous.
`K_2 SeO_4`
`rArr 39 x 2 + x + 64 = 142 + x`
`(142 + x) "g of" K_2 SeO_4 rArr x "g of" Se`
`100 "g of" K_2 SeO_4 rArr (x)/(14 + x) xx 100`
`:. (x)/(142 + x) xx 100 = 50`
`:. x = 142`.