321.

Which of the following orders regarding ionisation energy is correct?

• N > O > F

• N < O < F

• N > O < F

• N < O < F

Identify [A] and [B] in the following

${}_{89}{}^{227}\mathrm{Ac} \stackrel{-\mathrm{\beta }}{\to } \left[\mathrm{A}\right] \stackrel{-\mathrm{\alpha }}{\to } \left[\mathrm{B}\right] \stackrel{-\mathrm{\alpha }}{\to } \mathrm{Rn}$

• Po, Rn

• Th, Po

• Ra, Th

• Th, Ra

The electronic configuration 1s², 2s²2p⁶, 3s²3p⁶3d⁹ represents a

• metal atom

• non metal atom

• non-metallic anion

• metallic cation

In a given shell the order of screening effect is

• s > p > d > f

• s > p > f > d

• f > d > p > s

• s < p < d < f

Identify the least stable ion amongst the following.

• Li^-

• Be^-

• B^-

• C^-

The ionisation energy of hydrogen atom is 13.6eV. What will be the ionisation energy of He⁺?

• 13.6 eV

• 54.4 eV

• 122.4 eV

• Zero

Which element has highest electronegativity ?

• F

• He

• Ne

• Na

The correct order of radii is

• N <Be <B

• F^-<O^2-<N^3-

• Na< Li< K

• Fe³⁺< Fe²⁺< Fe⁴⁺

Which of the following element shows maximum valency ?

• Carbon

• Barium

• Nitrogen

• Sulphur

The metal used to recover copper from a solution of CuSO₄ is :

• Fe

• He

• Na

• Ag