1
WB JEE 2026
MCQ (Single Correct Answer)
+1
-0.25
Change Language

In a first order reaction,the concentration of reactant decreases from 400 moles lit $^{-1}$ to 50 moles lit ${ }^{-1}$ in $7 \cdot 5 \times 10^3 \mathrm{~s}$ .The rate constant of the reaction is(approximately)

A

$1 \times 10^{-2} \mathrm{~s}^{-1}$

B

$2.5 \times 10^{-3} \mathrm{~s}^{-1}$

C

$1 \times 10^{-5} \mathrm{~s}^{-1}$

D

$2.77 \times 10^{-4} \mathrm{~s}^{-1}$

2
WB JEE 2026
MCQ (Single Correct Answer)
+1
-0.25
Change Language

In the following reaction sequence, the product Y is

$$ \mathrm{Br}\left(\mathrm{CH}_2\right)_{12}-\mathrm{C} \equiv \mathrm{CH} \xrightarrow{\mathrm{NaNH}_2} \mathrm{X} \xrightarrow[\text { catalyst }]{\mathrm{H}_2, \text { Lindler }} \mathrm{Y} $$

A

WB JEE 2026 Chemistry - Hydrocarbons Question 1 English Option 1

B

WB JEE 2026 Chemistry - Hydrocarbons Question 1 English Option 2

C

$$ \mathrm{Br}\left(\mathrm{CH}_2\right)_{12}-\mathrm{CH}=\mathrm{CH}_2 $$

D

WB JEE 2026 Chemistry - Hydrocarbons Question 1 English Option 4

3
WB JEE 2026
MCQ (Single Correct Answer)
+1
-0.25
Change Language

The mass of an electron is $9 \cdot 1 \times 10^{-31} \mathrm{~kg}$ .If its K .E.is $3 \cdot 0 \times 10^{-25} \mathrm{~J}$ ,its wavelength is(approximately)

A

250 nm

B

400 nm

C

990 nm

D

850 nm

4
WB JEE 2026
MCQ (Single Correct Answer)
+1
-0.25
Change Language

The calculated magnetic moment for low spin $[\operatorname{Ru}(E D T A)]^{-}$isWB JEE 2026 Chemistry - Coordination Compounds Question 1 English

A

2.73 BM

B

1.73 BM

C

3.23 BM

D

0.00 BM