If the mass of 1 mole of water containing x % of heavy water is 19 g then the value of 'x is

Options

A. 0.3
B. 0.5
C. 0.75
D. 0.62

Answer

B

Explanation

Out of 1 mol of water ,number of moles of `D_2O = (x)/(100) xx 1 = 0.01 x`
Number of moles of `D_2O xx ` mass of `D_2O + ` number of moles of `H_2O xx ` mass of `H_2O = 19`
`0.01 x xx 20 +(1 - 0.01 x) xx 18 = 19`
`0.01 x xx 20 + 18 - 0.01x xx 18 = 19`
` 2 xx 0.01 x = 1`
x= 50