Question

A solution of glucose $\left(C_8{H}_{12}{O}_6\right)$ is isotonic with 5g of urea $\left(N{H}_{2}CON{H}_2\right)$ per litre of solution. The concentration of glucose is:

• A. 4 g/L
• B. 8 g/L
• C. 12 g/L
• D. 15 g/L

Answer 1

Answer: (D)

15 g/L

Isotonic solution means solution of same concentration i.e., Molarity of glucose $=$ Molarity of urea

Molarity of urea $=\frac{5}{60\times 1}=\frac{1}{12}$ $M$

Molarity of glucose $=\frac{1}{12}$ $M$

Concentration of glucose in $\frac{g}{L}=180\times \frac{1}{12}=15$ $g/L$

Hence, the correct option is $D.$