List of top Questions asked in JEE Main- 2021

Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Heavy water is used for the study of reaction mechanism.
Reason (R): The rate of reaction for the cleavage of O-H bond is slower than that of O-D bond.
Calgon is used for water treatment. Which of the following statement is $NOT$ true about Calgon?
(A) $HOCl + H _{2} O _{2} \rightarrow H _{3} O ^{+}+ Cl ^{-}+ O _{2}$
(B) $I _{2}+ H _{2} O _{2}+2 OH ^{-} \rightarrow 2 I ^{-}+2 H _{2} O + O _{2}$
Choose the correct option.
According to molecular orbital theory, the species among the following that does not exist is :
Which of the glycosidic linkage between galactose and glucose is present in lactose ?

In the following sequence of reactions the P is: 

The incorrect expression among the following is :
Sodium stearate $CH_3(CH_2)_{16}COO^- Na^+$ is an anionic surfactant which forms micelles in water. Choose the correct statement for it from the following :

Considering the hydrolysis of Benzonitrile ($C_6H_5CN$) in acidic medium (H₂O/H⁺), identify the product A :

Given below are two statements :
Statement I : The process of producing syn-gas is called gasification of coal.
Statement II : The composition of syn-gas is \( \text{CO} + \text{CO}_2 + \text{H}_2 \) (1 : 1 : 1).
In the light of the above statements, choose the most appropriate answer from the options given below :
Indicate the complex/complex ion which did not show any geometrical isomerism :
Match List - I and List - II. List - I: (a) Valium, (b) Morphine, (c) Norethindrone, (d) Vitamin B12 List - II: (i) Antifertility drug, (ii) Pernicious anaemia, (iii) Analgesic, (iv) Tranquilizer
Given below are two statements : Statement I : An allotrope of oxygen is an important intermediate in the formation of reducing smog. Statement II : Gases such as oxides of nitrogen and sulphur present in troposphere contribute to the formation of photochemical smog. In the light of the above statements, choose the correct answer from the options given below :
Water does not produce CO on reacting with:

The major product of the following reaction is: 


Consider the following reaction, the major product 'P' is: 

Which one of the following \( 0.10 \, \text{M} \) aqueous solutions will exhibit the largest freezing point depression ?
The gas 'A' is having very low reactivity reaches to stratosphere. It is non-toxic and non-flammable but dissociated by UV-radiations in stratosphere. The intermediates formed initially from the gas 'A' are:

The Major Product in the above reaction is : 

 

An organic compound "A" on treatment with benzene sulphonyl chloride gives compound B. B is soluble in dil. NaOH solution. Compound A is :
What are the products formed in sequence when excess of \(CO_2\) is passed in slaked lime ?
BOD values (in ppm) for clean water (A) and polluted water (B) are expected respectively as :
Which of the following are isostructural pairs? A. $SO _{4}^{2-}$ and $CrO _{4}^{2-}$ B. $SiCl _{4}$ and $TiCl _{4}$ C. $NH _{3}$ and $NO _{3}^{-}$ D. $BCl _{3}$ and $BrCl _{3}$ $BCl _{3}$ and $BrCl _{3}$
Which one of the following statements is FALSE for hydrophilic sols?
The denticity of an organic ligand, biuret is :