List of top Questions asked in WBJEE- 2010

The ratio of magnetic field and magnetic moment at the centre of a current carrying circular loop is $x$. When both the current and radius is doubled the ratio will be

The bond order of $CO$ molecule is

The roots of the quadratic equation $x^{2}-2\sqrt{3}x-22 = 0 $ are :

The value of the integral $\int\limits^{\pi/2}_{0}\sin^{5}\, x\,dx$ is

Solution of the differential equation $xdy - ydx = 0$ represents a

A wire of resistance $R$ is elongated $n$-fold to make a new uniform wire. The resistance of new wire

The displacement of a particle at time t is $x$, where $x = t^{4}-kt^{3}$ . If the velocity of the particle at time $t = 2$ is minimum, then

A stone falls freely from rest and the total distance covered by it in the last second of its motion equals the distance covered by it in the first three seconds of its motion. The stone remains in the air for

$\displaystyle\lim _{x \rightarrow 0} \frac{\sin |x|}{x}$ is equal to

On mixing certain alkane with chlorine and irradiating it with ultraviolet light,it forms only one mono-chloroalkane. The alkane is :

In the figure below, the capacitance of each capacitor is $3 \mu F$. The effective capacitance between $A$ and $B$ is :

A body is projected horizontally with a velocity of $u$ $ m/s$ at an angle $ \beta $ with the horizontal. The kinetic energy at the highest point is $( \frac{ 3}{ 4} )^{th}$ of the initial kinetic energy. The value of $ \beta $ is

In a common emitter configuration, a transistor has $\beta = 50$ and input resistance $1\, k\Omega$. If the peak value of a.c. input is $0.01\, V$ then the peak value of collector current is

The function $f\left(x\right) = \sec \left[\log\left(x+\sqrt{1+x^{2}}\right)\right]$ is

The value of $\frac{\log_{3} 5 \times \log_{25} 27 \times \log_{49} 7}{\log_{81} 3}$ is

If $f(5)=7$ and $f^{'}(5)=7$ then $\displaystyle\lim _{x \rightarrow 5} \frac{x f(5)-5 f(x)}{x-5}$ is given by

Which of the following orders regarding ionization energy is correct ?

When a manganous salt is fused with a mixture of $KNO_3$ and solid $NaOH$ the oxidation number of $Mn$ changes from $+2$ to

A body weighs 22.42 g and has a measured volume of 4.7 cc The possible errors in the measurement of mass and volume are 0.01 g and cc. Then the maximum error percentage in the density will be

$n$ identical droplets are charged to $V$ volt each. If they coalesce to form a single drop, then its potential will be

The general solution of the different equation $100\frac{d^{2}y}{dx^{2}}-20 \frac{dy}{dx}+y = 0 $ is

The degree of the differential equation $x = 1+\left(\frac{dy}{dx}\right)+\frac{1}{2!}\left(\frac{dy}{dx}\right)^{2}+\frac{1}{3!}\left(\frac{dy}{dx}\right)^{3} + .........$

$\int\sqrt{1+\cos\,x}\,dx$ is equal to

In hemoglobin the metal ion present is

Experimental investigations show that the intensity of solar radiation is maximum for a wavelength $480 \,nm$ in the visible region. Estimate the surface temperature of sun. (Given Wien's constant $b = 2.88\times10^{-3} \,mK.)$