1
MCQ (Single Correct Answer)

JEE Main 2017 (Online) 9th April Morning Slot

A solution is prepared by mixing 8.5 g of CH2Cl2 and 11.95 g of CHCl3 . If vapour pressure of CH2Cl2 and CHCl3 at 298 K are 415 and 200 mmHg respectively, the mole fraction of CHCl3 in vapour form is : (Molar mass of Cl = 35.5 g mol−1)
A
0.162
B
0.675
C
0.325
D
0.486
2
MCQ (Single Correct Answer)

JEE Main 2018 (Offline)

For 1 molal aqueous solution of the following compounds, which one will show the highest freezing point?
A
[Co(H2O)3 Cl3].3H2O
B
[Co(H2O)6] Cl3
C
[Co(H2O)5 Cl] Cl2.H2O
D
[Co(H2O)4 Cl2] Cl.2H2O

Explanation

We know,

$$\Delta {T_f}\, = \,im{K_f}$$

Where

$$\Delta {T_f}\, = \,$$ Depression in freezing point

i = no of ions or molecule

m = molality of solute

Kf = freezing point depression constant.

In this question m = 1 and Kf is constant.

So, $$\Delta {T_f}\,\, \propto \,\,i$$

Which solutions have more i, those solutions $$\Delta {T_f}\,$$ will be more.

Now,

Freezing point of a aqueous solution $${f_p} = \, - \,\Delta {T_f}$$

So, those solutions have more $$\Delta {T_f}$$ will have less freezing point

and $$\Delta {T_f}$$ will be more when value of i is more.

Now, for,

[ Co (H2O)6] Cl3 $$\rightleftharpoons$$ [ Co(H2O)6]3+ + 3Cl$$-$$

Value of i = 4 (no. of ions), 3 ions of Cl$$-$$

and one ion of [ Co (H2O)6]3+

[ Co (H2O)5 Cl ] Cl2 . H2O $$\rightleftharpoons$$ [ Co (H2O)5 Cl ]2+ + 2Cl$$-$$

Value of i = 3

[ Co (H2O)4 Cl2 ] Cl . 2H2O $$\rightleftharpoons$$ [ Co (H2O)4 Cl2 ] + + Cl$$-$$

Value of i = 2

and [ Co(H2O)3 Cl ] . 3H2O do not show ionization.

So, i = 1.

As, [ Co (H2O)3 Cl ]. 3H2O have lowest value of i,

So, it's freezing point will be maximum.
3
MCQ (Single Correct Answer)

JEE Main 2018 (Online) 15th April Evening Slot

Two 5 molal solutions are prepared by dissolving a non-electrolyte non-volatile solute separately in the solvents X and Y. The molecular weights of the solvents are Mx and My, respectively where Mx = $${3 \over 4}$$ My. The relative lowering of vapor pressure of the solution in X is ''m'' times that of the solution in Y. Given that the number of moles of solute is very small in comparison to that of the solvent, the value of ''m'' is :
A
$${4 \over 3}$$
B
$${3 \over 4}$$
C
$${1 \over 2}$$
D
$${1 \over 4}$$

Explanation

Relative lowering of vapour pressure,

   $${{\Delta P} \over P}$$   =   $${{{n_2}} \over {{n_1}}}$$

n2  =  Number of moles of solute

n1   =   Number of moles of solvent.

Given that,

Here is 5 molal solution, means 5 moles of solute are dissolved in 1 kg or 1000 g of solvent.

$$\therefore\,\,\,$$ Number of moles of solute = 5

Number of moles of solvent X  =  $${{1000} \over {{M_X}}}$$

Number of moles of solvent Y = $${{1000} \over {My}}$$

$$\therefore\,\,\,$$ $${\left( {{{\Delta \,P} \over P}} \right)_x}$$   =   $${5 \over {{{1000} \over {{M_x}}}}}$$ = $${{5{M_x}} \over {1000}}$$

$${\left( {{{\Delta \,P} \over P}} \right)_y}$$   =   $${5 \over {{{1000} \over {{M_y}}}}}$$   =   $${{5\,{M_y}} \over {1000}}$$

Accoding to the question.

$${{5{M_x}} \over {1000}}$$   =   m $$ \times $$ $${{5\,{M_y}} \over {1000}}$$

$$ \Rightarrow $$$$\,\,\,$$ Mx  =   m $$ \times $$ My

$$ \Rightarrow $$$$\,\,\,$$ $${3 \over 4}$$ My = m $$ \times $$ My   [as given,   Mx = $${3 \over 4}$$ My]

$$ \Rightarrow $$$$\,\,\,$$ m   =   $${3 \over 4}$$
4
MCQ (Single Correct Answer)

JEE Main 2018 (Online) 16th April Morning Slot

The mass of a non-volatile, non-electrolyte solute (molar mass = 50 g mol-1 ) needed to be dissolved in 114 g octane to reduce its vapour pressure to 75%, is :
A
37.5 g
B
75 g
C
150 g
D
50 g

Explanation

Molar mass of octane

(C8 H18) = 8 $$ \times $$ 12 + 18 = 114 g/mol

Let, $$\omega $$ is the mass of solute.

Relative lowering vapour pressure,

$${{\Delta P} \over P}$$ = $${{{\omega \over {50}}} \over {{\omega \over {50}} + {{114} \over {114}}}}$$

$$ \Rightarrow $$$$\,\,\,\,$$ $${{75} \over {100}}$$ = $${{{\omega \over {50}}} \over {{\omega \over {50}} + 1}}$$

$$ \Rightarrow $$ $$\,\,\,\,$$ $${3 \over 4}$$ $$\left( {{\omega \over {50}} + 1} \right) = {\omega \over {50}}$$

$$ \Rightarrow $$ $$\,\,\,\,$$ $$\omega $$ = 150 g

Questions Asked from Solutions

On those following papers in MCQ (Single Correct Answer)
Number in Brackets after Paper Name Indicates No of Questions
AIEEE 2002 (2)
keyboard_arrow_right
AIEEE 2003 (3)
keyboard_arrow_right
AIEEE 2004 (4)
keyboard_arrow_right
AIEEE 2005 (2)
keyboard_arrow_right
AIEEE 2006 (2)
keyboard_arrow_right
AIEEE 2007 (3)
keyboard_arrow_right
AIEEE 2008 (2)
keyboard_arrow_right
AIEEE 2009 (2)
keyboard_arrow_right
AIEEE 2010 (2)
keyboard_arrow_right
AIEEE 2011 (3)
keyboard_arrow_right
AIEEE 2012 (2)
keyboard_arrow_right
JEE Main 2014 (Offline) (1)
keyboard_arrow_right
JEE Main 2015 (Offline) (1)
keyboard_arrow_right
JEE Main 2016 (Offline) (1)
keyboard_arrow_right
JEE Main 2016 (Online) 9th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2016 (Online) 10th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2017 (Offline) (1)
keyboard_arrow_right
JEE Main 2017 (Online) 8th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2017 (Online) 9th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2018 (Offline) (1)
keyboard_arrow_right
JEE Main 2018 (Online) 15th April Evening Slot (1)
keyboard_arrow_right
JEE Main 2018 (Online) 16th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 9th January Evening Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 10th January Morning Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 10th January Evening Slot (3)
keyboard_arrow_right
JEE Main 2019 (Online) 11th January Morning Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 11th January Evening Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 12th January Morning Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 12th January Evening Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 8th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 8th April Evening Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 9th April Morning Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 9th April Evening Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 10th April Morning Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 10th April Evening Slot (2)
keyboard_arrow_right
JEE Main 2019 (Online) 12th April Morning Slot (1)
keyboard_arrow_right
JEE Main 2019 (Online) 12th April Evening Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 7th January Morning Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 7th January Evening Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 8th January Morning Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 2nd September Evening Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 3rd September Morning Slot (2)
keyboard_arrow_right
JEE Main 2020 (Online) 3rd September Evening Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 5th September Morning Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 6th September Morning Slot (1)
keyboard_arrow_right
JEE Main 2020 (Online) 6th September Evening Slot (1)
keyboard_arrow_right
JEE Main 2021 (Online) 24th February Morning Slot (1)
keyboard_arrow_right
JEE Main 2021 (Online) 24th February Evening Slot (1)
keyboard_arrow_right
JEE Main 2021 (Online) 16th March Evening Shift (1)
keyboard_arrow_right
JEE Main 2021 (Online) 22th July Evening Shift (2)
keyboard_arrow_right
JEE Main 2021 (Online) 31st August Morning Shift (1)
keyboard_arrow_right

EXAM MAP

Joint Entrance Examination

JEE Advanced JEE Main

Graduate Aptitude Test in Engineering

GATE CSE GATE ECE GATE ME GATE PI GATE EE GATE CE GATE IN

Medical

NEET