Solution MCQ Set-1

Q1. An aqueous solution of hydrochloric acid

Q2. Exactly $1\ g$ of urea dissolved in $75\ g$ of water gives a solution that boils at $100.114^\circ C$ at 760 torr. The molecular weight of urea is 60.1. The boiling point elevation constant for water is

Q3. $12\ g$ of urea is dissolved in 1 litre of water and $68.4\ g$ of sucrose is dissolved in 1 litre of water. The lowering of vapour pressure of first case is

Q4. At a particular temperature, the vapour pressures of two liquids A and B are respectively 120 and 180 mm of mercury. If 2 moles of A and 3 moles of B are mixed to form an ideal solution, the vapour pressure of the solution at the same temperature will be (in mm of mercury)

Q5. The freezing point of equimolal aqueous solution will be highest for

Q6. Which of the following $0.10\ m$ aqueous solutions will have the lowest freezing point ?

Q7. A solution containing $10\ g$ per $dm^3$ of urea (molecular mass = $60\ g\ mol^{–1}$) is isotonic with a $5\%$ solution of a non volatile solute. The molecular mass of this non volatile solute is

Q8. The vapour pressure of a solvent decreases by $10\ mm\ of\ Hg$ when a non-volatile solute was added to the solvent. The mole fraction of the solute in the solution is 0.2. What should be the mole fraction of the solvent if the decrease in the vapour pressure is to be $20\ mm\ of\ Hg$ ?

Q9. A solution containing $1.8\ g$ of a compound (empirical formula $CH_2O$) in $40\ g$ of water is observed to freeze at $–0.465^\circ C$. The molecular formula of the compound is ($K_f$ of water = $1.86\ kg\ K\ mol^{–1}$)

Q10. Which observation(s) reflect(s) colligative properties?
(i) A $0.5\ m\ NaBr$ solution has a higher vapour pressure than a $0.5\ m\ BaCl_2$ solution at the same temperature
(ii) Pure water freezes at the higher temperature than pure methanol
(iii) a $0.1\ m\ NaOH$ solution freezes at a lower temperature than pure water

Q11. The vapour pressure of benzene at $30^\circ C$ is $121.8\ mm$. By adding $15\ g$ of non-volatile solute in $250\ g$ of benzene, its vapour pressure is decreased to $120.2\ mm$. The molecular weight of solute is :

Q12. Pure benzene freezes at $5.45^\circ C$. A $0.374\ m$ solution of tetrachloroethane in benzene freezes at $3.55^\circ C$. The $K_f$ for benzene is:

Q13. $0.450\ g$ of urea (mol.wt.60) in $22.5\ g$ of water show $0.170^\circ C$ of elevation in boiling point. The molal elevation constant of water is:

Q14. The colligative property is not represented by :

Q15. $20\ g$ of a substance were dissolved in $500\ mL$ of water and the osmotic pressure of the solution was found to be $600\ mm$ of mercury at $15^\circ C$. The molecular weight of substance is :