Chemistry Solutions

Given below are two statements: one is labeled as Assertion (A) and the other is labeled as Reason (R)

Assertion (A): At 10°C, the density of a 5M solution of KCl [atomic masses of K % Cl are 39 & 35.5 g mol^-1 respectively is 'x' g ml^-1. The solution is cooled to -21°C. The molality of the solution will remain unchanged.

Reason (R) : The molality of a solution does not change with temperature as mass remains unaffected with temperature

In the light of the above statements, choose the correct answer from the options given below.

The depression in freezing point observed for a formic acid solution of concentration 0.5 mL L-1 is $0.0405°C.$ $$ Density of formic acid is 1.05 g mL-1. The Van't Hoff factor of the formic acid solution is nearly: (Given for water $K_f=1.86kkgmo{l}^{-1}$ ${}_{}{}^{}$ )

Boiling point of a 2% aqueous solution of a non-volatile solute A is equal to the boiling point of 8% aqueous of non-volatile solute B. The relation between molecular weights of A and B is

 1.80g of solute A was dissolved in 62.5cm³ of ethanol and freezing point of the solution was found to be 155.1 K . The molar mass of solute A is __________g mol^-1.

[Given: Freezing point of ethanol is 156.0 K. Density of ethanol is 0.80 g cm^-3. Freezing point depression constant of ethanol is 2.00 K kg mol^-1]

When a certain amount of solid A is dissolved in 100g of water at 25°C to make a dilute solution, the vapour pressure of the solution is reduced to one-half of that of pure water. The vapour pressure of pure water is 23.76 mmHg. The number of moles of solute A added is_________.

(Nearest Integer)

150g of acetic acid was contaminated with 10.2g ascorbic acid $\left(C_6{H}_8{O}_6\right)$  to lower down its freezing point by (x * 10^-1)°C. The value of x is _________. (Nearest integer)

(Given K_f = 3.9 K kg mol^-1; molar mass of ascorbic acid = 176 g mol^-1]

A Company dissolves 'x' amount of CO₂ at 298K in 1 litre of water to prepare soda water X = _________________ * 10^-3 g. (nearest integer)

The osmotic pressure of blood is 7.47 bar at 300K. To inject glucose to a patient intravenously, it has to isotonic with blood. The concentration of glucose solution in gL^-1 is __________.

(Molar mass of glucose = 180 g mol^-1 R = 0.083 L bar K^-1 mol^-1) Nearest integer)

A radioactive element has a half life of 200 days. The percentage of original activity remaining after 83 days is___________. (Nearest integer)

(Given : antilog 0.125 = 1.333, antilog 0.693 = 4.93)

The equation

k =   $\left(6.5*10^{12}{s}^{-1}\right)e^{-26000K/T}$

Is followed for the decomposition of compound A. The activation energy for the reaction is________ kJ mol^-1 [nearest integer]        (Given : R = 8.314 JK^-1 mol^-1)