Atomic weight of boron is 10.81 and it has two isotopes  and . Then, the ratio of atoms of  and  in nature would be

The constituents of atomic nuclei are believed to be

In the nucleus of ₁₁Na²³, the number of protons, neutrons and electrons are

An element A decays into element C by a two step process

Then

In a fission reaction

the binding energy per nucleon of X and Y is 8.5 MeV whereas of 236U is 7.6 MeV. The total energy liberated will be about

The activity of a radioactive sample is measured as 9750 counts/min at t = 0 and as 975 counts/min at t = 5 min. The decay constant is approximately

The stable nucleus that has a radius half that of Fe⁵⁶ is

A nucleus ruptures into two nuclear parts, which have their velocity ratio equal to 2 :1. What will be the ratio of their nuclear size (nuclear radius)?

Half-lives of two radioactive substances A and B are respectively 20 min and 40 min. Initially the samples of A and B have equal number of nuclei. After 80 min the ratio of remaining number of A and B nuclei is

The ratio of the radii of the nuclei ₁₃Al²⁷ and ₅₂Te¹²⁵ is approximately