The intensity of gamma radiation from a given source is I₀.On passing through 37.5 mm of lead it is reduced to I₀/8.The thickness of lead which will reduce it to I₀/2 is

A freshly prepared radioactive source of half life 2 hr emits radiation of intensity which is 64 times the permissible safe level. The minimum time after which it would be possible to work safely with this source is

The half-life of radioactive Radon is 3.8 days. The time at the end of which (1/20)th of the Radon sample will remain undecayed is (given log₁₀e = 0.4343)

If the distance between nuclei is 2 × 10^–13 cm, the density of nuclear material is

A gamma ray photon creates an electron-positron pair. If the rest mass energy of an electron is 0.5 MeV and the total kinetic energy of the electron-positron pair is 0.78 MeV,then the energy of the gamma ray photon must be

A radioactive substance contains 10000 nuclei and its half-life period is 20 days. The number of nuclei present at the end of 10 days is

If u denotes 1 atomic mass unit. One atom of an element has mass exactly equal to Au, where A is mass number of element.

The curve of binding energy per nucleon as a function of atomic mass number has a sharp peak for helium nucleus.This implies that helium

A radioactive substance has a half life of four months. Three fourth of the substance will decay in

If Avogadro number is 6 × 10²³, then number of protons,neutrons and electrons in 14 gms of ₆C¹⁴ are respecitvely