List of top Questions asked in JEE Main

In a period, the first ionisation enthalpy of the element at extreme left and the negative electron gain enthalpy of the extreme right element, except noble gases, are respectively.

An excess of \(AgNO_3\) is added to \(100\) mL of a \(0.05\) M solution of tetraaquodichloridochromium (III) chloride. The number of moles of \(AgCl\) precipitated will be ______\(\times 10^{-3}\). (Nearest integer)}

Given is a concentrated solution of a weak electrolyte \(A_xB_y\) of concentration \(c\) and dissociation constant \(K\). The degree of dissociation is given by:

Shown below is the structure of methyl acetate with three different \(\alpha\), \(\beta\) and \(\gamma\) carbon–oxygen bonds. The correct order of bond lengths of these bonds is :}

The correct order of first \((\Delta_iH_1)\) and second \((\Delta_iH_2)\) ionisation enthalpy values of Cr and Mn are:}

• [A.] \( \Delta_iH_1: Cr>Mn \)
• [B.] \( \Delta_iH_2: Cr>Mn \)
• [C.] \( \Delta_iH_1: Mn>Cr \)
• [D.] \( \Delta_iH_2: Mn>Cr \)

Choose the correct answer.

Which of the following sequences of hybridisation, geometry and magnetic nature are correct for the given coordination compounds?}

• [A.] \([NiCl_4]^{2-}\) -- \(sp^3\), tetrahedral, paramagnetic
• [B.] \([Ni(NH_3)_6]^{2+}\) -- \(sp^3d^2\), octahedral, paramagnetic
• [C.] \([Ni(CO)_4]\) -- \(sp^3\), tetrahedral, paramagnetic
• [D.] \([Ni(CN)_4]^{2-}\) -- \(dsp^2\), square planar, diamagnetic

Choose the correct answer.

Match List-I with List-II.

Choose the correct answer.

Given below are two statements:} Statement I:} A mixture of \(C_{12}H_{22}O_{11}\) (sugar) and \(NaCl\) can be separated by dissolving sugar in alcohol, due to differential solubility. Statement II:} Rose essence from rose petals is separated by steam distillation due to its high volatility and insolubility in \(H_2O\). Choose the correct answer.

An optically active alkyl bromide \(C_4H_9Br\) reacts with ethanolic KOH to form major compound [A] which reacts with bromine to give compound [B]. Compound [B] reacts with ethanolic KOH and sodamide to give compound [C]. One molecule of water adds to compound [C] on warming with mercuric sulphate and dilute sulphuric acid at \(333\,K\) to form compound [D]. The functional group in compound D is confirmed by :

Treatment of a gas \(X\) with a freshly prepared ferrous sulphate solution gives a compound \(Y\) as a brown ring. The compounds \(X\) and \(Y\) are :

The Bohr radius of a hydrogen like species is \(70.53\,\text{pm}\). The species and the stationary state \((n)\) are respectively. (Given: Hydrogen atom Bohr radius is \(52.9\,\text{pm}\)).

Decomposition of a hydrocarbon follows the equation} \[ k = (5.5 \times 10^{11}\, s^{-1})\, e^{\frac{-28000}{T}} \] The activation energy of reaction is _____ kJ mol\(^{-1}\). (Nearest Integer)} Given: \(R = 8.3\, J\,K^{-1}\,mol^{-1}\)}

Which of the following contain the same number of atoms? (Given : Molar mass in g mol\(^{-1}\) of H, He, O and S are \(1,4,16\) and \(32\) respectively)}

• [A.] \(2\,\text{g}\) of \(O_2\) gas
• [B.] \(4\,\text{g}\) of \(SO_2\) gas
• [C.] \(1400\,\text{mL}\) of \(O_2\) at STP
• [D.] \(0.05\,\text{L}\) of He at STP
• [E.] \(0.0625\,\text{mol}\) of \(H_2\) gas

Choose the correct answer from the options given below:

A parallel plate capacitor has a separation between plates of 0.885 mm. It has a capacitance of $1\,\mu\text{F}$ when the space between the plates is filled with an insulating material of resistivity $1 \times 10^{13}\,\Omega\,\text{m}$ and resistance $17.7 \times 10^{14}\,\Omega$. The relative permittivity of the insulating material is $\alpha \times 10^7$. The value of $\alpha$ is \underline{\hspace{2cm}}.

A gas balloon is going up with a constant velocity of 10 m/s. When this balloon reached a height of 75 m, a stone is dropped from it and balloon keeps moving up with the same velocity. The height of the balloon when the stone hits the ground is ________ m. (Take \(g = 10\) m/s²)

A current carrying circular loop of radius 2 cm with unit normal \(\hat{n} = \frac{\hat{k} + \hat{i}}{\sqrt{2}}\) is placed in a magnetic field, \(\vec{B} = B_0 (3\hat{i} + 2\hat{k})\). If \(B_0 = 4 \times 10^{-3}\) T and current \(I = 100\sqrt{2}\) A, the torque experienced by the loop is ________ Wb·A.

The output Y for the given inputs A and B to the circuit is:}

A solid cylinder having radius \(R\) and length \(L\) is slipping on a rough horizontal plane. At time \(t = 0\) the cylinder has a translational velocity \(v_0 = 49\) m/s, perpendicular to its axis and a rotational velocity \(v_0/4R\) about the centre. The time taken by the cylinder to start rolling is ________ seconds. (coefficient of kinetic friction \(\mu_k = 0.25\) and \(g = 9.8\) m/s²)

Light ray incident along a vector \(\vec{AO}\) (\(AO = 2\hat{i} - 3\hat{j}\)) emerges out along vector \(\vec{OB}\) (\(OB = C\hat{i} - 4\hat{j}\)) as shown in the figure below. The value of \(C\) is ________.

A spherical liquid drop of radius \(R\) acquires the terminal velocity \(v_1\) when falls through a gas of viscosity \(\eta\). Now the drop is broken into 64 identical droplets and each droplet acquires terminal velocity \(v_2\) falling through the same gas. The ratio of terminal velocities \(v_1/v_2\) is ________.

A 30 cm long solenoid has 10 turns per cm and area of 5 cm². The current through the solenoid coil varies from 2 A to 4 A in 3.14 s. The e.m.f. induced in the coil is \(\alpha \times 10^{-5}\) V. The value \(\alpha\) is ________.

A thin biconvex lens is prepared from the glass (\(\mu = 1.5\)) both curved surfaces of which have equal radii of 20 cm each. Left side surface of the lens is silvered from outside to make it reflecting. To have the position of image and object at the same place, the object should be placed from the lens at a distance of ________ cm.

The stored charge in the capacitor in steady state of the following circuit is ________ µC.

The frequency of oscillation of a mass \(m\) suspended by a spring is \(v_1\). If the length of the spring is cut to half, the same mass oscillates with frequency \(v_2\). The value of \(\frac{v_2}{v_1}\) is ________.

One mole of diatomic gas having rotational modes only is kept in a cylinder with a piston system. The cross-section area of the cylinder is 4 cm². The gas is heated slowly to raise the temperature by 1.2 °C during which the piston moves by 25 mm. The amount of heat supplied to the gas is ________ J. (Atmospheric pressure = 100 kPa, \(R = 8.3\) J/mol·K) (Neglect mass of the piston)