List of practice Questions

What is the correct stability order of \( KO_2, RbO_2, CsO_2 \)?
The heights of the transmitting and receiving antennas are 33.8 m and 64.8 m respectively. The maximum distance between the antennas for satisfactory communication in line of sight mode is:
(Radius of the earth = 6400 km)
Identify the pair of species having the same energy from the following: (The number given in the bracket corresponds to the principal quantum number (n) in which the electron is present.)
Identify the pair of elements in which the number of s-electrons to p-electrons ratio is 2:3:
In a series LCR circuit, if the current leads the source voltage, then:
If the amplitude of the magnetic field part of a harmonic electromagnetic wave in vacuum is \( 270 \) nT, the amplitude of the electric field part of the wave is:
At room temperature, gaseous hydrogen is bombarded with a beam of electrons of 13.6 eV energy. The series to which the emitted spectral line belongs to:
The half-life of a radioactive substance is 12 minutes. The time gap between 28\% decay and 82\% decay of the radioactive substance is:
An element consists of a mixture of three isotopes A, B, and C of masses \( m_1 \), \( m_2 \), and \( m_3 \) respectively. If the relative abundances of the three isotopes A, B, and C is in the ratio 2:3:5, the average mass of the element is:
The concentration of electrons in an intrinsic semiconductor is \( 6 \times 10^{15} \, m^{-3} \). On doping with an impurity, the electron concentration increases to \( 4 \times 10^{22} \, m^{-3} \). In thermal equilibrium, the concentration of the holes in the doped semiconductor is:
A particle of charge \( 2 C \) is moving with a velocity \( (3\hat{i} + 4\hat{j}) \) m/s in the presence of magnetic and electric fields. If the magnetic field is \( ( \hat{i} + 2\hat{j} + 3\hat{k} ) \) T and the electric field is \( (-2\hat{k}) \) NC\(^{-1}\), then the Lorentz force on the particle is:
A rectangular coil of 400 turns and \(10^{-2} \, \text{m}^2\) area, carrying a current of 0.5 A is placed in a uniform magnetic field of 1 T such that the plane of the coil makes an angle of 60° with the direction of the magnetic field. The initial moment of force acting on the coil in Nm is:
The most exotic diamagnetic materials are:
Two circular coils of radii \(r_1\) and \(r_2\) (\(r_1 \ll r_2\)) are placed coaxially with their centers coinciding. The mutual inductance of the arrangement is:
The efficiency of a reversible heat engine working between two temperatures is 50\%. The coefficient of performance of a refrigerator working between the same two temperatures but in reverse direction is:
The total internal energy of 4 moles of a diatomic gas at a temperature of \(27^\circ C\) is: (Universal gas constant \( R = 8.31 \, \text{J mol}^{-1} \text{K}^{-1} \))
A car travelling at a speed of \(54 \, \text{kmph}\) towards a wall sounds a horn of frequency \(400 \, \text{Hz}\). The difference in the frequencies of two sounds, one received directly from the car and the other reflected from the wall, noticed by a person standing between the car and the wall is: (Speed of sound in air is \(335 \, \text{m/s}\))
For a combination of two convex lenses of focal lengths \( f_1 \) and \( f_2 \) to act as a glass slab, the distance of separation between them is:
If a ray of light passes through an equilateral prism such that the angle of incidence and the angle of emergence are both equal to 70\% of the angle of the prism, then the angle of minimum deviation is:
The energy required to take a body from the surface of the earth to a height equal to the radius of the earth is \( W \). The energy required to take this body from the surface of the earth to a height equal to twice the radius of the earth is:
A steel wire of length 3 m and a copper wire of length 2.2 m are connected end to end. When the combination is stretched by a force, the net elongation is 1.05 mm. If the area of cross-section of each wire is 6 mm², then the load applied is: (Young’s moduli of steel and copper are respectively \(2 \times 10^{11} \, \text{Nm}^{-2}\) and \(1.1 \times 10^{11} \, \text{Nm}^{-2}\)).
The height of water level in a tank of uniform cross-section is 5 m. The volume of the water leaked in 5 s through a hole of area \(2.4~mm^{2}\) made at the bottom of the tank is (Assume the level of the water in the tank remains constant and acceleration due to gravity \(=10~ms^{-2}\))
The work done in increasing the diameter of a soap bubble from 2 cm to 4 cm is (Surface tension of soap solution \(=3.5\times10^{-2}Nm^{-1}\))
The temperature on a Fahrenheit temperature scale that is twice the temperature on a Celsius temperature scale is:
The temperatures of equal masses of three different liquids A, B, and C are \(15^\circ C\), \(24^\circ C\), and \(30^\circ C\) respectively. The resultant temperature when liquids A and B are mixed is \(20^\circ C\) and when liquids B and C are mixed is \(26^\circ C\). Then the ratio of specific heat capacities of the liquids A, B, and C is: