List of top Chemistry Questions asked in JEE Main

Decreasing order of the hydrogen bonding in following forms of water is correctly represented by
A. Liquid water
B. Ice
C. Impure water 
Choose the correct answer from the options given below:

' $25$ volume' hydrogen peroxide means
$Ka _1, Ka _2$ and $Ka _3$ are the respective ionization constants for the following reactions (a), (b) and (c)
(a) $H _2 C _2 O _4 \rightleftharpoons H ^{+}+ HC _2 O _4^{-}$
(b) $HC _2 O _4^{-} \rightleftharpoons H ^{+}+ HC _2 O _4^{2-}$
(c) $H _2 C _2 O _4 \rightleftharpoons 2 H ^{+}+ C _2 O _4^{2-}$
The relationship between $K _{ a _1}, K _{ a _2}$ and $K _{ a _3}$ is given as
In the wet tests for identification of various cations by precipitation, which transition element cation doesn't belong to group IV in qualitative inorganic analysis ?

An organic compound 'A' with emperical formula $C _6 H _6 O$ gives sooty flame on burning Its reaction with bromine solution in low polarity solvent results in high yield of $B .B$ is

Increasing order of stability of the resonance structures is: Choose the correct answer from the options given below:
The number of incorrect statement/s from the following is/are ____
A. Water vapours are adsorbed by anhydrous calcium chloride.
B. There is a decrease in surface energy during adsorption.
C. As the adsorption proceeds, $\Delta H$ becomes more and more negative.
D. Adsorption is accompanied by decrease in entropy of the system.
A short peptide on complete hydrolysis produces 3 moles of glycine (G), two moles of leucine $( L )$ and two moles of valine $( V )$ per mole of peptide The number of peptide linkages in it are ______
An indicator ' X ' is used for studying the effect of variation in concentration of iodide : on the rate of reaction of iodide ion with $H_2O_2 $ at room temp. The indicator ' X ' forms blue colored complex with compound ' A ' present in the solution. The indicator ' X ' and compound 'A' respectively are
Total number of acidic oxides among $N_2O_3,NO_2, N_2O,Cl_2O_7,SO_2,CO,CaO,Na_2O$ and NO is ____ .
A doctor prescribed the drug Equanil to a patient. The patient was likely to have symptoms of which disease?
The number of paramagnetic species from the following is ________
$ {\left[ Ni ( CN )_4\right]^{2-} \cdot\left[ Ni ( CO )_4\right],\left[ NiCl _4\right]^{2-}} $ $ {\left[ Fe ( CN )_6\right]^{4-},\left[ Cu \left( NH _3\right)_4\right]^{2+}}$ $ {\left[ Fe ( CN )_6\right]^{3-} \text { and }\left[ Fe \left( H _2 O \right)_6\right]^{2+}}$
During the qualitative analysis of $SO _3^2$ using dilute $H _2 SO _4, SO _2$ gas is evolved which turns $K _2 Cr _2 O _7$ solution (acidified with dilute $H _2 SO _4$ ) :
Match the following:
Column-IColumn-II
(A) Zone refining(P) pig iron
(B) Electrolysis(Q) Al
(C) Reverberatory furnace(R) Si
(D) Blast furnace(S) Cu
Statement I: For colloidal particles, the values of colligative properties are of small order as compared to values shown by true solutions at the same concentration 
Statement II: For colloidal particles, the potential difference between the fixed layer and the diffused layer of the same charges is called the electrokinetic potential or zeta potential
In the light of the above statements, choose the correct answer from the options given below
The number of given orbitals which have electron density along the axis is _____ $p _x, p _y, p _z, d _{x y}, d _{y z}, d _{x z}, d _z 2, d _x{ }^2-y^2$
The correct representation in six-membered pyranose form for the following sugar $ [X]$ is 
At $27^{\circ} C$, a solution containing $25 \,g$ of solute in $2500 \,mL$ of solution exerts an osmotic pressure of $400 \,Pa$. The molar mass of the solute is ____ $g\,mol ^{-1}$. (Nearest integer)
(Given : $R =0.083 \,L\,bar\, K ^{-1} \,mol ^{-1}$ )
Number of compounds from the following which will not dissolve in cold $NaHCO _3$ and $NaOH$ solutions but will dissolve in hot $NaOH$ solution is______
Compounds
The water quality of a pond was analysed and its BOD was found to be 4. The pond has

Statement-I: Noradrenaline is one of the neurotransmitter. 

Statement-II: Low level of noradrenaline is not cause of depression in humans.

In light of the above statements, choose the correct answer from the options given below

Given below are two statements: One is labelled as Assertion A and the other is labelled as Reason $R$ 
Assertion A : Antihistamines do not affect the secretion of acid in stomach 
Reason R : Antiallergic and antacid drugs work on different receptors 
In the light of the above statements, choose the correct answer from the options given below:
The $Cl - Co - Cl$ bond angle values in a fac- $\left[ Co \left( NH _3\right)_3 Cl _3\right]$ complex is/are:
Iron oxide $FeO$, crystallises in a cubic lattice with a unit cell edge length of $50 \mathring{A}$ If density of the $FeO$ in the crystal is $40\, g \,cm ^{-3}$, then the number of $FeO$ units present per unit cell is ______ (Nearest integer) Given: Molar mass of $Fe$ and $O$ is $56$ and $16 \, g \, mol ^{-1}$ respectively $N _{ A }=60 \times 10^{23} mol ^{-1}$

The oxidation state of phosphorus in hypophosphoric acid is + _____