Among the following groupings which represent the collection of isoelectronic species.

• NO⁺, C${}_2^{2-}$, C${}_2^{-}$, CO

• N₂, C${}_2^{2-}$, CO, NO

• CO, NO⁺, CN^-, C${}_2^{2-}$

• NO, CN^-, N₂, O${}_2^{-}$

Which element has maximum first ionisation potential?

• Cs

• F

• Na

• He

Atomic radii of which metals are same?

• Cr, Mn, Cu

• Cr, Fe, Co

• Sc, Ti, Zn

• V, N, Cr

Smallest among these species is

• lithium

• lithium ion

• hydrogen

• helium

Chloride ion and potassium ion are isoelectronic. Then

• potassium ion is relatively bigger

• depends on the other cation and anion

• their size are same

• chloride ion is bigger than potassium ion

Which metal is used to make alloy steel for armour plates, safes and helmets?

• Al

• Mn

• Cr

• Pb

The element with atomic number 36 belongs to ........ block in the periodic table.

• p

• s

• f

• d

Among Na⁺, Na, Mg and Mg²⁺ the largest particle is

• Mg²⁺

• Mg

• Na

• Na⁺

Mg²⁺ is isoelectronic with

• Cu²⁺

• Zn²⁺

• Na⁺

• Ca²⁺

The electronic configuration of Cr³⁺ is

• [Ar] 3d⁴ 4s²

• [Ar] 3d³ 4s⁰

• [Ar] 3d² 4s¹

• [Ar] 3d⁵ 4s¹