Modern Physics Mock Tests

A radioactive sample has 75% of its nuclei decayed after 4 days. Its half-life is:

In a nuclear fusion reaction, two deuterium nuclei (²H) combine to form helium-3 (³He) and a neutron. If the mass defect is 0.006 u, the energy released is: (1 u = 931.5 MeV)

A radioactive substance has a half-life of 10 days. The time taken for 87.5% of the substance to decay is:

Two laser beams one of wavelength 640 nm and the other 400 nm have same unit flux of photons. Their powers are in the ratio:

A metal surface has a work function of 2.5 eV. The threshold frequency is: (h = 6.63 × 10⁻³⁴ J·s, 1 eV = 1.6 × 10⁻¹⁹ J)

In the Bohr model of the hydrogen atom, the radius of the nth orbit is proportional to:

The energy of a photon of wavelength 600 nm is approximately: (h = 6.63 × 10⁻³⁴ J·s, c = 3 × 10⁸ m/s)

A nuclear reaction converts 1 kg of mass completely into energy. The energy released is: (c = 3 × 10⁸ m/s)