List of practice Questions

The $S.I$ unit of activity of a radioactive sample is
Position-time graph for motion with zero acceleration is
Phenol on heating with alcoholic $KOH$ and chloroform - undergoes
The correct order of reducing character of alkali metals is
Freundlich adsorption isotherm equation is
The best coagulant for the precipitation of $Fe ( OH )_{3}$ is
A car moving with a speed of $50 \,km\, h^{-1}$ can be stopped by applying brakes after moving atleast $6 \,m$. If the same car is moving at a speed of $100 \,km\, h^{-1}$ the minimum stopping distance is
Zeigler-Natta catalyst is used to prepare
The maximum power dissipated in an external resistance R, when connected to a cell of emf E and internal resistance r, will be
The value of $ \cos \frac{\pi }{7}.\,\cos \frac{2\pi }{7}.\,\cos \frac{4\pi }{7} $ is equal to
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