Test: Periodic Trends in Properties of Elements (May 10) - NEET MCQ

'a' Represents covalent radius which is the distance between the nuclei of two bonded atoms 'b' represents van der waals'radius which is the distance between nuclei of two closest molecules.

Size of atoms decreases with increases in atomic number in a period.

Third ionisation energy is higher than second ionisation energy which is higher than the first ionisation energy.

After losing one electron, the atom will get a stable configuration and its second ionisation energy will be very high. Hence, option (b) is correct.

Beryllium halides are covalent in nature. This is due to small size and high charge of Be²⁺ ion i.e., it has high polarising power. However, the halides of the other alkaline earth metals (fluorides, chlorides, bromides and iodides) are ionic solids.

X has highest IE₁ and IE₂ hence, it is a noble gas. Y has low lE₁, but very high IE₂ hence, it is an alkali metal.
Z has low lE₁ than IE₂ and IE₂ is even lower than IE₂ of alkali metal hence, it is an alkaline earth metal.

Given X = 1s² 2s² 2p⁶ 3s¹
Y = 1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹
Less energy is required to remove an electron from X than Y, because the distance between the nucleus and valence shell in Y is greater as compared to X.

I.E. in a group decreases and reactivity increases.

Electron affinity of noble gases is zero.