List of top Questions asked in JEE Main- 2021

Four dice are thrown simultaneously and the numbers shown on these dice are recorded in \(2 \times 2\) matrices. The probability that such formed matrix have all different entries and are non-singular, is :

Let \(S_n\) denote the sum of first n-terms of an arithmetic progression. If \(S_{10} = 530\), \(S_5 = 140\), then \(S_{20} - S_6\) is equal to:

100 ml of 0.0018% (w/v) solution of \(\mathrm{Cl^-}\) ion was the minimum concentration of \(\mathrm{Cl^-}\) required to precipitate a negative sol in one h. The coagulating value of \(\mathrm{Cl^-}\) ion is _________ (Nearest integer)

Diamond has a three dimensional structure of C atoms formed by covalent bonds. The structure of diamond has face centred cubic lattice where 50% of the tetrahedral voids are also occupied by carbon atoms. The number of carbon atoms present per unit cell of diamond is ____________.

Which one of the following gases is reported to retard photosynthesis?

Potassium chlorate is prepared by electrolysis of KCl in basic solution as shown by following equation.
\(\mathrm{6OH^- + Cl^- \rightarrow ClO_3^- + 3H_2O + 6e^-}\)
A current of xA has to be passed for 10h to produce 10.0g of potassium chlorate. The value of x is ____________. (Nearest integer)
(Molar mass of \(\mathrm{KClO_3}\) = 122.6 g \(\mathrm{mol^{-1}}\), F = 96500 C)

4g equimolar mixture of NaOH and \(\mathrm{Na_2CO_3}\) contains x g of NaOH and y g of \(\mathrm{Na_2CO_3}\). The value of x is ____________ g. (Nearest integer)

An aqueous solution of \(\mathrm{NiCl_2}\) was heated with excess sodium cyanide in presence of strong oxidizing agent to form \(\mathrm{[Ni(CN)_6]^{2-}}\). The total change in number of unpaired electrons on metal centre is _______________.

For a given chemical reaction A \(\rightarrow\) B at 300 K the free energy change is \(-49.4\) kJ \(\mathrm{mol^{-1}}\) and the enthalpy of reaction is 51.4 kJ \(\mathrm{mol^{-1}}\). The entropy change of the reaction is _____________ \(\mathrm{JK^{-1}\,mol^{-1}}\).

\(\mathrm{PCl_5(g) \rightarrow PCl_3(g) + Cl_2(g)}\)
In the above first order reaction the concentration of \(\mathrm{PCl_5}\) reduces from initial concentration 50 mol \(\mathrm{L^{-1}}\) to 10 mol \(\mathrm{L^{-1}}\) in 120 minutes at 300 K. The rate constant for the reaction at 300 K is x \(\times\) \(10^{-2}\) \(\mathrm{min^{-1}}\). The value of x is __________. [Given log5 = 0.6989]

The single largest industrial application of dihydrogen is :

The correct order of their reactivity towards hydrolysis at room temperature is :

Consider two chemical reactions (A) and (B) that take place during metallurgical process:
(A) \(\mathrm{ZnCO_{3(s)} \xrightarrow{\Delta} ZnO_{(s)} + CO_{2(g)}}\)
(B) \(\mathrm{2ZnS_{(s)} + 3O_{2(g)} \xrightarrow{\Delta} 2ZnO_{(s)} + 2SO_{2(g)}}\)
The correct option of names given to them respectively is :

In Carius method, halogen containing organic compound is heated with fuming nitric acid in the presence of :

\(\mathrm{Cu^{2+}}\) salt reacts with potassium iodide to give

Bakelite is a cross-linked polymer of formaldehyde and :

Benzene on nitration gives nitrobenzene in presence of \(\mathrm{HNO_3}\) and \(\mathrm{H_2SO_4}\) mixture, where :

Major product P of above reaction, is :

The hybridisations of the atomic orbitals of nitrogen in \(\mathrm{NO_2^-}\), \(\mathrm{NO_2^+}\) and \(\mathrm{NH_4^+}\) respectively are.

Which one of the following statements is not true about enzymes?

Which one of the following species doesn't have a magnetic moment of 1.73 BM, (spin only value)?

Consider the above reaction, compound B is :

The major product (P) in the following reaction is :

Metallic sodium does not react normally with :

Spin only magnetic moment of an octahedral complex of \(\mathrm{Fe^{2+}}\) in the presence of a strong field ligand in BM is :