List of practice Questions

Two oxides of a metal contain $36.4 \%$ and $53.4 \%$ of oxygen by mass respectively. If the formula of the first oxide is $M _{2} O$, then that of the second is
The standard enthalpy of formation of $C_2H_{4(g)}, CO_{2(g)}$ and $H_2O_{(l)}$ are $52, -394$ and $-286\, kJ\, mol^{-1}$ respectively. Then the amount of heat evolved by burning $7\, g$ of $C_2H_{4(g)}$ is
A gardener pushes a lawn roller through a distance $ 20\,m $ . If he applies a force of $ 20\,kg\,wt $ in a direction inclined at $ 60^{\circ} $ to the ground, the work done by him is
Chemically unreactive three different gases $A, B$ and $C$ of molecular masses $16, 32$ and $64$ are enclosed in a vessel at constant temperature till equilibrium is reached. Which of the following statements is true?
Magnetic flux of $10 \mu Wb $ is linked with a coil, when a current of 2 mA flows through it. What is the self inductance of the coil?
The current gain of a common base transistor circuit is 0.96. On changing the emitter current by 10.0 mA, the change in the base current will be
Water is used as a coolant in automobile radiators owing to its high
When $6.3\, g$ of sodium bicarbonate are added to $30.0\, g$ of acetic acid solution, the residual solution is found to weigh $33.0\, g$. The mass of carbon dioxide released in the reaction is
How many $ 1\,\mu F $ capacitors must be connected in parallel to store a charge of $1\, C$ with a potential of $110\, V$ across the capacitors?
$G = \left\{\begin{bmatrix} x&x \\[0.3em] x & x \end{bmatrix} , x \text{ is a nonzero real number} \right\}$ is a group with respect to matrix multiplication. In this group, the inverse of $\begin{bmatrix} \frac{1}{3} &\frac{1}{3} \\[0.3em] \frac{1}{3} & \frac{1}{3} \end{bmatrix}$ is
$\begin{vmatrix} {Sin \alpha}&{ \cos\alpha} &Sin ({\alpha+ \delta })\\ {Sin \beta}&{ Cos \beta}& Sin ({\beta+\delta}) \\ {Sin \gamma}&{ Cos \gamma}&Sin ({\gamma+\delta})\\ \end{vmatrix} $ is equal to
A solid sphere rolls down two different inclined planes of same height, but of different inclinations. ln both cases
A man stands in a narrow, steep-sided valley. When he shouts he hears two echoes, one after l s and other after 2 s. If the velocity of sound in air is 330 m/s, the width of the valley is
A circular disc of radius $R$ is removed from a bigger circular disc of radius $2 R$ such that the circumferences of the discs touch. The centre of mass of the new disc is at a distance $\alpha R$ from the centre of the bigger disc. The value of $\alpha$ is
An electron in the hydrogen atom jumps from excited state n to the ground state. The wavelength so emitted illuminates a photosensitive material having work function $2.75 \,eV$. If the stopping potential of the photoelectron is $10 \,V$ , then the value of $n$ is
Fusion reaction takes place at high temperature because
A body is moving with velocity $30\, ms$ towards east After 10 s its velocity becomes $40 \,ms$ towards north. The average acceleration of the body is
According to kinetic theory of gases
According to the Bohr Theory, which of the following transitions in the hydrogen atom will give rise to the least energetic photon?
A solid compound $XY$ has $NaCl$ structure. If the radius of the cation is $100\, pm$, the radius of the anion $(Y^-)$ will be -
Suppose $ P(2,\,y,\,z) $ lies on the line through $ A(3,-1,4) $ and $ B(-4,2,1) $ . Then, the value of z is equal to
Consider the following four conditions $(a-d)$ and select the correct pair of them as adaptation to environment in desert lizards. The conditions: 1. Burrowing in soil to escape high temperature. 2. Losing heat rapidly from the body during high temperature. 3. Bask in sun when temperature is low. 4. Insulating body due to thick fatty dermis.
In $n$ is an odd positive integer and $(1+x +x^2 +x^3)^n =\displaystyle\sum_{r=0}^{3n} a_rx^r$ then $a_0 -a_1+a_2-a_3 +\dots -a_{3n}$ is equal to
Angles of elevation of the top of a tower from three points (collinear) $A, B$ and $ C$ on a road leading to the foot of the tower are $30^\circ$, $45^\circ$ and $60^\circ$ respectively. The ratio of $AB$ to $BC$ is
The derivative of $tan ^{-1}[\frac{Sin x}{1+ Cos x}]$ with respect to $tan^{-1}[\frac{Cos x}{1+Sin x}]$ is