List of top Questions asked in JEE Main- 2021

The lines \(x=ay-1=z-2\) and \(x=3y-2=bz-2\), \((ab\ne0)\) are coplanar, if :

If \([x]\) denotes the greatest integer less than or equal to \(x\), then the value of the integral \(\int_{-\pi/2}^{\pi/2}[[x]-\sin x]\,dx\) is equal to :

The value of
\(\tan\left(2\tan^{-1}\left(\frac{3}{5}\right)+\sin^{-1}\left(\frac{5}{13}\right)\right)\)
is equal to :

At \(20^\circ\) C, the vapour pressure of benzene is 70 torr and that of methyl benzene is 20 torr. The mole fraction of benzene in the vapour phase at \(20^\circ\) above an equimolar mixture of benzene and methyl benzene is _____________ \(\times 10^{-2}\). (Nearest integer)

The inactivation rate of a viral preparation is proportional to the amount of virus. In the first minute after preparation, 10% of the virus is inactivated. The rate constant for viral inactivation is ___________ \(\times 10^{-3}\) \(\mathrm{min^{-1}}\). (Nearest integer)

[Use : \(\ln 10 = 2.303\); \(\log_{10} 3 = 0.477\); property of logarithm : \(\log x^y = y \log x\)]

250 mL of 0.5 M NaOH was added to 500 mL of 1 M HCl. The number of unreacted HCl molecules in the solution after complete reaction is ___________ \(\times\) \(10^{21}\). (Nearest integer)

(\(N_A = 6.022 \times 10^{23}\))

The number of nitrogen atoms in a semicarbazone molecule of acetone is ______________.

To synthesize 1.0 mole of 2-methylpropan-2-ol from Ethylethanoate ___________ equivalents of \(\mathrm{CH_3MgBr}\) Reagent will be required. (Integer value)

The Azimuthal quantum number for the valence electrons of \(\mathrm{Ga^+}\) ion is ___________.

(Atomic number of Ga = 31)

\(2\mathrm{SO_2(g)} + \mathrm{O_2(g)} \rightleftharpoons 2\mathrm{SO_3(g)}\)

In an equilibrium mixture, the partial pressures are

\(P_{\mathrm{SO_3}} = 43\) kPa; \(P_{\mathrm{O_2}} = 530\) Pa and \(P_{\mathrm{SO_2}} = 45\) kPa. The equilibrium constant \(K_P =\) ___________ \(\times 10^{-2}\). (Nearest integer)

The spin-only magnetic moment value for the complex \([\mathrm{Co(CN)_6}]^{4-}\) is __________ BM.

[At. no. of Co = 27]

A s-block element (M) reacts with oxygen to form an oxide of the formula \(\mathrm{MO_2}\). The oxide is pale yellow in colour and paramagnetic. The element (M) is :

The metal that can be purified economically by fractional distillation method is :

The conditions given below are in the context of observing Tyndall effect in colloidal solutions :

(A) The diameter of the colloidal particles is comparable to the wavelength of light used.

(B) The diameter of the colloidal particles is much smaller than the wavelength of light used.

(C) The diameter of the colloidal particles is much larger than the wavelength of light used.

(D) The refractive indices of the dispersed phase and the dispersion medium are comparable.

(E) The dispersed phase has a very different refractive index from the dispersion medium.

Choose the most appropriate conditions from the options given below :

The number of lone pairs of electrons on the central I atom in \(\mathrm{I_3^-}\) is ____________.

Chemical nature of the nitrogen oxide compound obtained from a reaction of concentrated nitric acid and \(\mathrm{P_4O_{10}}\) (in 4 : 1 ratio) is :

Green chemistry in day-to-day life is in the use of :

The set in which compounds have different nature is :

Given below are two statements. One is labelled as Assertion A and the other is labelled as Reason R.

Assertion A : Sharp glass edge becomes smooth on heating it upto its melting point.

Reason R : The viscosity of glass decreases on melting.

Choose the most appropriate answer from the options given below.

Given below are two statements : One is labelled as Assertion A and other is labelled as Reason R.

Assertion A : The dihedral angles in \(\mathrm{H_2O_2}\) in gaseous phase is \(90.2^\circ\) and in solid phase is \(111.5^\circ\).

Reason R : The change in dihedral angle in solid and gaseous phase is due to the difference in the intermolecular forces.

Choose the most appropriate answer from the options given below for A and R.

Orlon fibres are made up of :

In the given reaction
3-Bromo-2, 2-dimethyl butane \(\xrightarrow{\mathrm{C_2H_5OH}}\) 'A' (Major Product)
Product A is :

Which among the above compound/s does/do not form Silver mirror when treated with Tollen's reagent?

For above chemical reactions, identify the correct statement from the following :

Identify the incorrect statement from the following