Question

Maltose is converted to 'A' by Maltase. The mole fraction of 'A' in $10\%$ (w/w) aq. solution is approximately.

• A. $0.989$
• B. $0.012$
• C. $0.1$
• D. $0.017$

Answer 1

Answer: (A)

$0.989$

10% w/w solution of glucose in water means that 10 g of glucose in present in 100 g of the solution i.e., 10 g of glucose is present in (100 - 10) g = 90 g of water.

Molar mass of glucose $\left(C_6{H}_{12}{O}_6\right)=6\times 12+12\times 1+6\times 16=180gmo{l}^{-1}$

Then, number of moles of glucose = 10 / 180 mol

= 0.056 mol

$x_w=molefractionofA$

Molality of solution = 0.056 mol / 0.09kg = 0.62 m

Number of moles of water = 90g / 18g mol-1 = 5 mol

Mole fraction of glucose $\left(x_g\right)$ = 0.056 / ( 0.056+5) = 0.011

And, mole fraction of water $x_w$ = 1 - $x_g$

= 1 - 0.011 = 0.989