List of practice Questions

Given $K_p$ for $2AO_2 + O_2 \rightleftharpoons 2AO_3$ is $4 \times 10^{10}$. Find $K_p'$ for $3AO_3 \rightleftharpoons 3AO_2 + \frac{3}{2} O_2$.
Which of the following is used as stabilizer for H$_2$O$_2$?
In a common emitter amplifier, the collector resistance is 3 times the base resistance. If the common emitter current amplification factor is 60, then the power gain of the amplifier is:
The intrinsic carrier concentration of a semiconductor is $1.2\times10^{16}$ m$^{-3}$. On doping with an impurity, the electron concentration becomes $20\times10^5$ times initial concentration. The concentration of holes in the doped semiconductor is:
Optical communication using fibres is performed in the frequency range of:
According to Bohr's theory of hydrogen atom, the approximate angular momentum of electron in H atom in the ground state is ($h = 6.62 \times 10^{-34}$ Js):
Observe the elements from H (Z=1) to Ca (Z=20). How many elements have no unpaired electrons in their ground state?
Among Li, Na, O, S, the elements having the most negative electron gain enthalpy and least negative electron gain enthalpy respectively are:
Ionization enthalpies of the elements X, Y, Z having successive atomic numbers respectively are 2080, 496, 737 kJ mol$^{-1}$. X, Y, Z are:
A resistor of resistance 160 $\Omega$, an inductor of 280 mH, and a capacitor are connected in series to an AC source of 80 V, 50 Hz. If the circuit is in resonance, the potential difference across the capacitor is:
The potential difference between the plates of a parallel plate capacitor is changing at the rate of $3.5\times10^6$ V/s. If the displacement current is 7 A, the capacitance of the capacitor is:
If the de Broglie wavelength of a proton accelerated through a potential difference $V_1$ is same as the de Broglie wavelength of an alpha particle accelerated through $V_2$, then $V_1 : V_2 = $
The ratio of frequencies of second line of Lyman series and third line of Balmer series of hydrogen atom is:
If the half-life of a radioactive material is 5 days, then the ratio of the number of atoms disintegrated in 10 and 15 days is:
If the energy released in the fission of one uranium nucleus is 200 MeV, then the number of fissions per second required to produce 20 MW is:
If a charge of 3 nC is placed at each vertex of a cube of side 3 m, then the electric potential at the centre of the cube is:
If the magnitude of electric field in a conductor is $200\ \text{NC}^{-1}$ and the current density is $10^9\ \text{Am}^{-2}$, then the resistivity of the material of the conductor is:
If a 20 W bulb and a 100 W fan are used for 5 and 15 hours a day respectively, then the electrical energy consumed in a period of 30 days is:
Two charged particles enter a uniform magnetic field normally. If the ratio of the specific charges of the two particles is 2:3, then the ratio of the times taken by the two particles to complete one revolution is:
The magnetic field (in $10^{-4}$ T) at the centre of a toroid of mean radius 10 cm with 200 turns and carrying a current of 2.5 A is:
The properties required for a material to be used as the core of an electromagnet are:
A train is moving with a speed of 198 kmph. If the distance between the rails is 120 cm and the vertical component of earth's magnetic field is $0.25 \times 10^{-4}$ T, the induced emf between the ends of the axle of the train is:
The specific heat capacity of one mole of water is (R is the universal gas constant):
In a medium, a source produces 60 crests and 60 troughs in a time of 0.2 s. If the distance between a crest and its adjacent trough is 100 cm, then the speed of sound in the medium is:
An observer moves towards a source at rest with a speed of 25% of the speed of sound in air. If the frequency of the sound emitted by the source is 200 Hz, then the frequency of sound heard by the observer is: