Question

Which of the following sets of solutions of urea (mol. mass $60 \,g\, mol^{-1}$) and sucrose (mol. mass $342\, g \,mol^{-1}$) is isotonic?

• A. $9.1 \,gL^{-1}$ urea and $6.0 \,gL^{-1}$ sucrose
• B. $3.0 \,gL^{-1}$ urea and $3.0 \,gL^{-1}$ sucrose
• C. $6.0 \,gL^{-1}$ urea and $9.0 \,gL^{-1}$ sucrose
• D. $3.0 \,gL^{-1}$ urea and $17.1 \,gL^{-1}$ sucrose

Answer 1

Answer: (D)

$3.0 \,gL^{-1}$ urea and $17.1 \,gL^{-1}$ sucrose

Answer 2

Isotonic solutions are those solutions which have same osmotic pressure at a given temperature

Formula for osmotic pressure, $\pi =CRT$