Atoms and Nucle...

Assertion The force of repulsion between atomic nucleus and α–particle varies with distance according to inverse square law
Reason Rutherford did α–particle scattering experiment

Assertion The positively charged nucleus of an atom has a radius of almost 10^–15 m
Reason In α–particle scattering experiment, the distance of closest approach forα–particles is ≃ 10^–15m

Assertion According to classical theory, the proposed path of an electron in Rutherford atom model will be parabolic
Reason According to electromagnetic theory an accelerated particle continuously emits radiation

Assertion Electrons in the atom are held due to coulomb forces
Reason The atom is stable only because the centripetal force due to Coulomb\'s law is balanced by the centrifugal force

Assertion The mass of a nucleus can be either less than or more than the sum of the masses of nucleons present in it
Reason The whole mass of the atom is considered in the nucleus

Assertion Hydrogen atom consists of only one electron but its emission spectrum has many lines
Reason Only Lyman series is found in the absorption spectrum of hydrogen atom whereas in the emission spectrum, all the series are found

Assertion For the scattering of α–particles at large angles, only the nucleus of the atom is responsible
Reason Nucleus is very heavy in comparison to electrons

Assertion Cobalt-60 is useful in cancer therapy
Reason Cobalt-60 is source of γ–radiations capable of killing cancerous cell

Assertion Amongst alpha, beta and gamma rays, α–particle has maximum penetrating power
Reason The alpha particle is heavier than beta and gamma rays