The energy of the electron in the 3d-orbital is less than that in the 4s-orbital in the hydrogen atom.

Gamma rays are electromagnetic radiations of wavelengths of 10^-6 to 10^-5 cm

Elements of the same mass number but of different atomic numbers are known as ____.

Complete and balance the following equations:

Cl₂ + OH^- $$\to$$ Cl^- + ClO^-