List of top Chemistry Questions asked in JEE Main

Consider the following reactions. 

\(PCl_3+H_2→A+HCL\)

\(A+H_2o→B+HCL\)

The number of ionisable protons present in the product B is

Which of the following can be used to prevent the decomposition of \(H_2O_2\)?
Resistance of a conductivity cell (cell constant 129 m–1) filled with 74.5 ppm solution of KCI is 100 Ω (labelled as solution 1). When the same cell is filled with KCl solution of 149 ppm, the resistance is 50 Ω (labelled as solution 2). The ratio of molar conductivity of solution 1 and solution 2 is \(\frac{\Lambda_1}{\Lambda_2} = x \times 10^{-3}\). The value of x is _________. (Nearest integer)
(Given : molar mass of KCl is 74.5 g mol–1).
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A) : At 10°C, the density of a 5 M 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.

CNG is an important transportation fuel. When 100 g CNG is mixed with 208 g oxygen in vehicles, it leads to the formation of CO2 and H2O and produced large quantity of heat during this combustion, then the amount of carbon dioxide, produced in grams is _____. [nearest integer]
 [Assume CNG to be methane]

Optical activity of an enantiomeric mixture is +12.6° and the specific rotation of (+) isomer is +30°. The optical purity is _______%.
Nitrogen gas is obtained by thermal decomposition of
0.2 g of an organic compound was subjected to estimation of nitrogen by Duma’s method in which volume of N2 evolved (at STP) was found to be 22.400 mL. The percentage of nitrogen in the compound is _____. [nearest integer] 
(Given : Molar mass of N2 is 28 g mol–1, Molar volume of N2 at STP : 22.4L)

An organic compound ‘A’ on reaction with NH3 followed by heating gives compound B. Which on further strong heating gives compound C(C8H5NO2). Compound C on sequential reaction with ethanolic KOH, alkyl chloride and hydrolysis with alkali gives a primary amine. The compound A is :

A chemical which stimulates the secretion of pepsin is

In the following reaction,
the % yield for reaction I is 60% and that of reaction II is 50%. The overall yield of the complete reaction is _______%. [Nearest integer].

the % yield for reaction I is 60% and that of reaction II is 50%.

Two isomers ‘A’ and ‘B’ with molecular formula C4H8 give different products on oxidation with KMnO4/H+ results in effervescence of a gas and gives ketone. The compound ‘A’ is

In the given reaction,

Fig. 

The number of π electrons present in the product ‘P’ is_____.

In the above reaction, 5 g of toluene is converted into benzaldehyde with 92% yield. The amount of benzaldehyde produced is______ × 10–2 g. (Nearest integer).
The reaction of
 Reaction with bromine and KOH
with bromine and \(KOH\) gives \(RNH_2\) as the end product. Which one of the following is the intermediate product formed in this reaction?
Which of the following conditions or reaction sequence will NOT give acetophenone as the major product?
Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason R. 
Assertion A: Thin layer chromatography is an adsorption chromatography. 
Reason R: A thin layer of silica gel is spread over a glass plate of suitable size inthin layer chromatography which acts as an adsorbent. 
In the light of the above statements, choose the correct answer from the options given below
An element A of group1 shows similarity to an element B belonging to group 2. If A has maximum hydration enthalpy in group 1 then B is:
Which of the following pairs is not isoelectronic species? 
(At. no. Sm, 62; Er, 68; Yb, 70; Lu, 71; Eu, 63; Tb, 65; Tm, 69)

Among the following structures, which will show the most stable enamine formation? 
(Where Me is –CH3)

Among the following, basic oxide is:
Match List-I with List-II
List-I (Compound)List-II (Shape)
(A) \(BrF_5\)(I) bent
(B) \([CrF_6]^{3–}\)(II) square pyramidal
(C) \(O_3\)(III) trigonal bipyramidal
(D) \(PCI_5\)(IV) octahedral
Choose the correct answer from the options given below :

The activation energy of one of the reactions in a biochemical process is 532611 J mol–1. When the temperature falls from 310 K to 300 K, the change in rate constant observed is k300 = x × 10–3 k310. The value of x is ______.

[Given: ln10 = 2.3, R = 8.3 JK–1 mol–1]

The polymer, which can be stretched and retains its original status on releasing the force is

Match List-I with List-II :
 

List-IList-II
(A) Negatively charged sol(I) Fe2O3.xH2O
(B) Macromolecular colloid(II) CdS sol
(C) Positively charged sol(III) Starch
(D) Cheese(IV) a gel


Choose the correct answer from the options given below: