NEW
New Website Launch
Experience the best way to solve previous year questions with mock tests (very detailed analysis), bookmark your favourite questions, practice etc...
1

JEE Main 2021 (Online) 27th August Morning Shift

Numerical
The reaction that occurs in a breath analyser, a device used to determine the alcohol level in a person's blood stream is

$$2{K_2}C{r_2}{O_7} + 8{H_2}S{O_4} + 3{C_2}{H_6}O \to 2C{r_2}{(S{O_4})_3} + 3{C_2}{H_4}{O_2} + 2{K_2}S{O_4} + 11{H_2}O$$

If the rate of appearance of Cr2(SO4)3 is 2.67 mol min$$-$$1 at a particular time, the rate of disappearance of C2H6O at the same time is _____________ mol min$$-$$1. (Nearest integer)
Your Input ________

Answer

Correct Answer is 4

Explanation

$$\left( {{{Rate\,of\,disappearance\,of\,{C_2}{H_6}O} \over 3}} \right)$$

$$ = \left( {{{Rate\,of\,disappearance\,of\,C{r_2}{{(S{O_4})}_3}} \over 2}} \right)$$

$$ \Rightarrow \left( {{{2.67\,mol/\min \, \times 3} \over 2}} \right) = $$ rate of disappearance of C2H6O.

$$\Rightarrow$$ Rate of disappearance of C2H6O = 4.005 mol/min.
2

JEE Main 2021 (Online) 26th August Evening Shift

Numerical
The reaction rate for the reaction

[PtCl4]2$$-$$ + H2O $$\rightleftharpoons$$ [Pt(H2O)Cl3]$$-$$ + Cl$$-$$

was measured as a function of concentrations of different species. It was observed that $${{ - d\left[ {{{\left[ {PtC{l_4}} \right]}^{2 - }}} \right]} \over {dt}} = 4.8 \times {10^{ - 5}}\left[ {{{\left[ {PtC{l_4}} \right]}^{2 - }}} \right] - 2.4 \times {10^{ - 3}}\left[ {{{\left[ {Pt({H_2}O)C{l_3}} \right]}^ - }} \right]\left[ {C{l^ - }} \right]$$.

where square brackets are used to denote molar concentrations. The equilibrium constant Kc = ____________ . (Nearest integer)
Your Input ________

Answer

Correct Answer is 50

Explanation

[PtCl4]2$$-$$ + H2O $$\rightleftharpoons$$ [Pt(H2O)Cl3]$$-$$ + Cl$$-$$

$${{ - d{{\left[ {PtC{l_4}} \right]}^{ - 2}}} \over {dt}} = 4.8 \times {10^{ - 5}}\left[ {PtC{l_4}^{ - 2}} \right] - 2.4 \times {10^{ - 3}}[Pt({H_2}O)C{l_3}][\mathop u\limits^o ]$$

$$ \Rightarrow {K_{eq}} = {{{k_f}} \over {{k_b}}} = {{4.8 \times {{10}^{ - 5}}} \over {2.4 \times {{10}^{ - 3}}}} = 0.02$$
3

JEE Main 2021 (Online) 26th August Evening Shift

Numerical
The overall stability constant of the complex ion [Cu(NH3)4]2+ is 2.1 $$\times$$ 1013. The overall dissociations constant is y $$\times$$ 10$$-$$14. Then y is __________. (Nearest integer)
Your Input ________

Answer

Correct Answer is 5

Explanation



Given ks = 2.1 $$\times$$ 1013

Kd = $${1 \over {{k_s}}}$$ = 4.7 $$\times$$ 10$$-$$14

$$\therefore$$ y = 4.7 $$ \approx $$ 5
4

JEE Main 2021 (Online) 26th August Morning Shift

Numerical
The following data was obtained for chemical reaction given below at 975 K.

2NO(g) + 2H2(g) $$\to$$ N2(g) + 2H2O(g)



The order of the reaction with respect to NO is ___________. [Integer answer]
Your Input ________

Answer

Correct Answer is 1

Explanation

7 $$\times$$ 10$$-$$9 = K $$\times$$ (8 $$\times$$ 10$$-$$5)x (8 $$\times$$ 10$$-$$5)y ......... (1)

2.1 $$\times$$ 10$$-$$8 = K $$\times$$ (24 $$\times$$ 10$$-$$5)x (8 $$\times$$ 10$$-$$5)y ....... (2)

$${1 \over 3} = {\left( {{1 \over 3}} \right)^x} \Rightarrow x = 1$$

Questions Asked from Chemical Kinetics and Nuclear Chemistry

On those following papers in Numerical
Number in Brackets after Paper Indicates No. of Questions
JEE Main 2022 (Online) 24th June Evening Shift [ Memory Based ] (1)
JEE Main 2021 (Online) 31st August Evening Shift (1)
JEE Main 2021 (Online) 31st August Morning Shift (2)
JEE Main 2021 (Online) 27th August Evening Shift (1)
JEE Main 2021 (Online) 27th August Morning Shift (1)
JEE Main 2021 (Online) 26th August Evening Shift (2)
JEE Main 2021 (Online) 26th August Morning Shift (1)
JEE Main 2021 (Online) 27th July Evening Shift (1)
JEE Main 2021 (Online) 25th July Evening Shift (1)
JEE Main 2021 (Online) 22th July Evening Shift (1)
JEE Main 2021 (Online) 20th July Evening Shift (1)
JEE Main 2021 (Online) 20th July Morning Shift (1)
JEE Main 2021 (Online) 18th March Evening Shift (1)
JEE Main 2021 (Online) 18th March Morning Shift (1)
JEE Main 2021 (Online) 17th March Evening Shift (1)
JEE Main 2021 (Online) 17th March Morning Shift (1)
JEE Main 2021 (Online) 16th March Evening Shift (1)
JEE Main 2021 (Online) 16th March Morning Shift (1)
JEE Main 2021 (Online) 26th February Evening Shift (1)
JEE Main 2021 (Online) 25th February Evening Shift (1)
JEE Main 2021 (Online) 25th February Morning Shift (1)
JEE Main 2021 (Online) 24th February Evening Shift (1)
JEE Main 2021 (Online) 24th February Morning Shift (1)
JEE Main 2020 (Online) 6th September Evening Slot (2)
JEE Main 2020 (Online) 4th September Evening Slot (1)
JEE Main 2020 (Online) 4th September Morning Slot (1)
JEE Main 2020 (Online) 7th January Morning Slot (1)

Joint Entrance Examination

JEE Main JEE Advanced WB JEE

Graduate Aptitude Test in Engineering

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

Medical

NEET

CBSE

Class 12