The ratio of the first three radii of Bohr's atom is:

A statement of Assertion followed by a statement of Reason is given. Choose the correct answer out of the following options.

Assertion : Energy of $$2 \mathrm{~s}$$ orbital of Hydrogen is less than the energy of the $$2 \mathrm{~s}$$ orbital of Lithium.

Reason : Energies of orbitals in the same subshell decrease with increase in atomic number.

Given below are 4 subatomic particles travelling with the same velocity "v". Which of them will have the shortest wavelength?

$$[A]=\text { Proton }[B]=\text { Neutron. }[C]=\text { Alpha particle. }[D]=\text { Electron. }$$

The mass number of an element $$\mathrm{X}$$ is 175 with 104 neutrons in its nucleus. Into which one of the following orbitals will the last electron enter?