List of top Questions asked in WBJEE

The standard reduction potential $E^o$ for half reations are $Zn = Zn^{2+} + 2e^- ;\,\,E^o = +0.76 V$ $Fe = Fe^{2+} + 2e^-;\,\, E^o = + 0.41 V$ The EMF of hte cell reaction $Fe^{2+} + Zn = Zn^{2+} + Fe$ is

$20\, mL$ of $0.2\, M \,NaOH$ is added to $50\, mL$ of $0.2\, M$ acetic acid. The pH of this solution after mixing is $(Ka = 1.8 \times 10^{-5})$

$2\,gm$ of metal carbonate is neutralized completely by $100 \,mL$ of $0.1 \,(N) \,HCl$. The equivalent weight of metal carbonate is

The normality of $30$ volume $H_2O_2$ is

The pH of an aqueous solution of $CH_3COONa$ of concentrated $C(M)$ is given by

If the focal length of the eye-piece of a telescope is doubled, its magnifying power $(m)$ will be

A body floats in water with $40\%$ of its volume outside water. When the same body floats in an oil, $60\%$ of its volume remains outside oil. The relative density of oil is

The sequence $\log \,a$, $\log \frac{a^{2}}{b}, \,\log \frac{a^{3}}{b^{2}}, ...........$ is

If the equilibrium constants of the following equilibria ${SO_{2(g)} +\frac{1}{2}O2 <=> SO3$ $ and\, 2SO_{3(g)} <=> 2SO_{2(g)} +O_{2(g)}}$ are given by $K_1$ and $K_2$ respectively, which of the following relations is correct

Two soap bubbles of radii $x$ and $y$ coalesce to constitute a bubble of radius $z$. Then $z$ is equal to

Two cells with the same e.m.f. $E$ and different internal resistances $r_1$ and $r_2$ are connected in series to an external resistance $R$. The value of $R$ so that the potential difference across the first cell be zero is

$^{15}C_{3} +\,^{15}C_{5} + .. ...+\,^{15}C_{15} $ will be equal to

An ideal gas is compressed isothermally until its pressure is doubled and then allowed to expand adiabatically to regain its original volume ($? = 1.4$ and $2^{-1.4} = 0.38$). The ratio of the final to initial pressure is

A diver at a depth of $12\, m$ in water $\bigg(\mu = \frac{4}{3}\bigg)$ sees the sky in a cone of semi vertical angle

The charge on the capacitor of capacitance $C$ shown in the figure below will be

If $A = \begin{bmatrix}3&x-1\\ 2x+3&x+2\end{bmatrix}$ is a symmetric matrix, then the value of $x$ is

The number of solutions of $2\,\sin x + \cos\, x = 3$ is

The coordinates of a moving point $p$ are $(2t^2 + 4, 4t + 6)$. Then its locus will be a

If the three points $A(1,6), B(3, -4)$ and $C(x, y)$ are collinear then the equation satisfying by $x$ and $y$ is

If $\sin\,\theta$ and $\cos \theta $ are the roots of the equation $ax^2 - bx + c = 0$, then $a, b$ and $c$ satisfy the relation

Two aromatic compounds having formula $C_7H_8O$ which are easily identifiable by $FeCl_3$ solution test (violet colouration) are

Let $\tan \,\alpha = \frac{a}{a+1}$ and $\tan \,\beta = \frac{1}{2a + 1}$ then $\alpha + \beta$ is

Reaction of formaldehyde and ammonia gives

The amount of the heat released when $20\,mL$ $0.5\, M\, NaOH$ is mixed with $100\, mL\, 0.1\, M\, HCl$ is $x\, kJ$. The heat of neutralization is

Which of the following compounds has maximum volatility?