List of top Questions asked in WBJEE

In the extraction of genetic material (DNA), which enzyme is not used?
A uniform rope of length 4 m and mass 0.4kg is held on a frictionless table in such a way that 0.6m of the rope is hanging over the edge. The work done to pull the hanging part of the rope onto the table is, (Assuming g=10m/s2) 
A metal ($M$) forms two oxides. The ratio $M:O$ (by weight) in the two oxides are $25:4$ and $25:6$. The minimum value of atomic mass of $M$ is
The de-Broglie wavelength ($\lambda$) for electron ($e$), proton ($p$), and He²⁺ ion ($\alpha$) are in the following order, Speed of $e$, $p$, and $\alpha$ are the same
A golf ball of mass $50$ gm placed on a tee is struck by a golf club. The speed of the ball as it leaves the tee is $100$ m/s, and the time of contact on the ball is $0.02$ s. If the force decreases to zero linearly with time, then the force at the beginning of the contact is
Choose the correct statement for the [Ni(CN)4]²⁻ complex ion (Atomic no. of Ni = 28)
Which of the statements are incorrect?
Which of the following is the correct set of four quantum numbers ($n$, $l$, $m$, $s$)?
Three particles, each of mass $m$ grams situated at the vertices of an equilateral $\Delta ABC$ of side $a$ cm (as shown in the figure). The moment of inertia of the system about a line $AX$ perpendicular to $AB$ and in the plane of $\Delta ABC$ in $g$-cm² units will be:
Three particles, each of mass
A particle is subjected to two simple harmonic motions in the same direction having equal amplitudes and equal frequency. If the resultant amplitude is equal to the amplitude of the individual motion, the phase difference $(\delta)$ between the two motions is
In a closed circuit there is only a coil of inductance $L$ and resistance $100\ \Omega$. The coil is situated in a uniform magnetic field. All of a sudden, the magnetic flux linked with the circuit changes by $5$ Weber. What amount of charge will flow in the circuit as a result?
As shown in the figure, a rectangular loop of length $a$ and width $b$ and made of a conducting material of uniform cross-section is kept in a horizontal plane where a uniform magnetic field of intensity $B$ is acting vertically downward. The resistance per unit length of the loop is $\lambda \, \Omega / m$. If the loop is pulled with uniform velocity $v$ in a horizontal direction, which of the following statement(s) is/are true?
rectangular loop of length 'a' and width 'b' and made of a conducting material of uniform cross-section
Certain amount of an ideal gas is taken from its initial state 1 to final state 4 through the paths 1 → 2 → 3 → 4 as shown in the figure AB, CD, EF are all isotherms. If $v_p$ is the most probable speed of the molecules, then:
Certain amount of an ideal gas is taken from its initial state 1 to final
One mole of a diatomic ideal gas undergoes a process shown in the P-V diagram. The total heat given to the gas (In 2 = 0.7) is:
One mole of a diatomic ideal gas undergoes a process
Consider a thermodynamic process where internal energy $U \equiv A p^2 V$ (A = Constant). If the process is performed adiabatically, then
One mole of an ideal monatomic gas expands along the polytrope $P V^3 = \text{constant}$ from $V_1$ to $V_2$ at a constant pressure $P_1$. The temperature during the process is such that molar specific heat $C_v = \frac{3R}{2}$. The total heat absorbed during the process can be expressed as
Consider two concentric conducting spheres of radii $R$ and $2R$ respectively. The inner sphere is given a charge $+Q$. The other sphere is grounded. The potential at $r = \frac{3R}{2}$ is
A Zener diode having a breakdown voltage $V_z = 6$ V is used in a voltage regulator circuit as shown in the figure. The minimum current required to pass through the Zener to act as a voltage regulator is $10$ mA and the maximum allowed current through the Zener is $40$ mA. The maximum value of $R_\delta$ for Zener to act as a voltage regulator is
A Zener diode having a breakdown voltage
A body of mass $m$ is thrown vertically upward with speed $\sqrt{3}v_e^2$, where $v_e$ is the escape velocity of a body from earth surface. The final velocity of the body is
The electric potential for an electric field directed parallel to the X-axis is shown in the figure. Choose the correct plot of electric field strength.
A battery of emf E and internal resistance r is connected with an external resistance R as shown in figure. The battery will act as a constant voltage source if:
A battery of emf E and internal resistance r
Suppose in a hypothetical world the angular momentum is quantized to be even integral multiples of $\frac{h}{2}$. The largest possible wavelength emitted by hydrogen atoms in the visible range in a world according to Bohr's model will be (consider $h_e = 1224$ MeV-fm)
A body of mass $m$ is thrown with velocity $u$ from the origin of a coordinate axes at an angle with the horizon. The magnitude of the angular momentum of the particle about the origin at time $t$ when it is at the maximum height of the trajectory is proportional to
The expression $A(A + B) + (B + AA)(A + B)$ simplifies to
A particle is moving in the $x$-$y$ plane according to $r = b \cos \omega t \hat{i} + b \sin \omega t \hat{j}$. Where $\omega$ is constant. Which of the following statement(s) is/are true?