List of top Questions asked in JEE Main

According to Lewis theory, the total number of σ bond-pairs and lone pair of electrons around the central atom of \(XeO_6^{4-}\) ion is ______.

Identify the colour of compound 'X' in the sequence of the reaction [assuming the Lassaigne's test for Nitrogen/Sulfur or Nitroprusside test].

Match the LIST-I with LIST-II

Statement I: The structure of Maltose is given below: Maltose is a non-reducing sugar.

Statement II: The structure of Lactose is given below: Lactose is a reducing sugar.

In the light of the above statements, choose the correct answer:

Product C of the following reaction sequence will be [assuming sequence: Aniline $\xrightarrow{Br_2/H_2O}$ A $\xrightarrow{NaNO_2/HCl}$ B $\xrightarrow{H_3PO_2}$ C]

Amongst the following, the total number of compounds soluble in aqueous NaOH at room temperature is:

Match the LIST-I with LIST-II

An alkene (X) on ozonolysis followed by reduction gives following products. [Assuming products are Glyoxal and Formaldehyde/Acetone based on standard paper context]. The alkene (X) is:

Increasing order of electron withdrawing power of following functional groups is:
a. -CN
b. -COOH
c. -NO₂
d. -I

Match the LIST-I with LIST-II

Correct statements from the following are:
A. Potassium dichromate is an oxidising agent and it oxidises FeSO₄ to Fe₂(SO₄)₃ in acidic medium.
B. Sodium dichromate can be used as primary standard in volumetric estimation.
C. CrO₄²⁻ and Cr₂O₇²⁻ are interconvertible in aqueous solution by varying the pH of the solution.
D. Cr-O-Cr bond angle in Cr₂O₇²⁻ is 126°.
Choose the correct answer:

If the half life of a first order reaction is \(6.93 \text{ minutes}\) then the time required for completion of \(99 %\) of the reaction will be ____ minutes.
(Given : \(\log 2 = 0.3010\))}

The values of pressure equilibrium constant recorded at different temperatures for the following equilibrium reaction have been given below:
\(A(g) \rightleftharpoons B(g) + C(g)\)}

The magnitude of \(\frac{\Delta H^\circ}{R}\) calculated from the above data is ____. (Nearest integer)}

One mole of phenol is treated with dilute \(HNO_3\) at \(298 \text{ K}\) to give a mixture of products. The mixture is separated by steam distillation. The steam volatile compound (X) is separated. The increase in percentage of oxygen in (X) with respect to phenol is ____ \(\times 10^{-1}\) %.
(Given molar mass in \(\text{g mol}^{-1}\) H:1, C:12, N:14, O:16)}

In an estimation of sulphur by Carius method \(0.2 \text{ g}\) of the substance gave \(0.6 \text{ g}\) of \(BaSO_4\). The percentage of sulphur in the substance is ____ %.
(Given molar mass in \(\text{g mol}^{-1}\) S : 32, \(BaSO_4 : 231\))}

Consider the following species:
\(BrF_5, XeF_5^-, BF_4^-, ICl_4^-, XeF_4, SF_4, NH_4^+, ClF_3, XeF_2, ICl_2^-\)
Number of species having \(sp^3d\) hybridized central atom is ____.

Given below are two statements:
Statement I: Sodium dichromate and potassium dichromate are classified as primary standards in titrimetric analysis.
Statement II: Phenolphthalein is a weak base, therefore it dissociates in acidic medium.

Identify the correct statements.
A. Glucose exists in two anomeric forms.
B. Anomers of glucose differ in configuration at C-1 in cyclic hemiacetal structure.
C. Melting point of \(\alpha\)-anomer of glucose is greater than \(\beta\)-anomer.
D. Specific rotation of \(\alpha\)-anomer is \(+19^\circ\) while for \(\beta\)-anomer is \(+112^\circ\).
E. \(\alpha\) and \(\beta\) anomers of glucose are prepared by crystallization of saturated glucose solution at \(303 \text{ K}\) and \(371 \text{ K}\) respectively.

Identify the incorrect statements.

Consider compounds A, B and C with following structural formulae
\(A = CH_3 - CH_2 - CH_2 - CH_2 - CH_2 - OH\)
\(B = CH_2 = CH - CH_2 - CH_2 - CH_3\)
\(C = HO - CH_2 - CH_2 - CH(OH) - CH_3\)
For the conversion of B from A, reagent (D) required is ____ and structural formula of product (E) obtained when C undergoes same reaction using excess reagent (D) is ____.

Benzyl isocyanide can be obtained from}

For the following Friedel Craft's alkylation reaction, which of the statements are correct?}

A. Major product is n-propyl benzene.
B. iso-propyl carbocation intermediate is also generated.
C. Multiple substitution is inevitable.
D. Introducing electron-donating substituent on benzene will not produce any alkyl benzene.

"P" is a hydrocarbon of molecular formula:- \(C_8H_{14}\). On ozonolysis, "P" forms "Q". "Q" on treatment with alkali under reflux condition produces "R", which on treatment with \(I_2 / NaOH\) gives a yellow precipitate. Acidification of the solution gives "S". The structure of "S" is given below:-}

Given below are two statements:
Statement I: On the basis of inductive effect, the order of stability of alkyl carbanions is \(CH_3^->CH_3-CH_2^->(CH_3)_2CH^->(CH_3)_3C^-\).
Statement II: Allyl and benzyl carbanions are more stabilised by inductive effect and not by resonance effect.

Given below are two statements:
Statement I: Each electron in \(e_g\) orbitals destabilizes the orbitals by \(+0.6 \Delta_o\) and each electron in the \(t_{2g}\) orbitals stabilizes the orbitals by \(-0.4 \Delta_o\) in an octahedral field on the basis of crystal field theory.
Statement II: All the d-orbitals of the transition metals have the same energy in their free atomic state but when a complex is formed the ligands destroy the degeneracy of these orbitals on the basis of crystal field theory.