In case of heteronuclear diatomics of the type AB, where A is more electronegative than B, bonding molecular orbital resembles the character of A more than that of B. The statement

• is false

• is true

• cannot be evaluated since data is not sufficient

• is true only for certain systems

The ground state electronic configuration of CO molecule is

• 1σ²2σ²1$\mathrm{\pi }$⁴3σ²

• 1σ²2σ²3σ²1$\mathrm{\pi }$²2$\mathrm{\pi }$²

• 1σ²2σ²1$\mathrm{\pi }$²3σ²2$\mathrm{\pi }$²

• 1σ²1$\mathrm{\pi }$²2σ²2σ²

In borax the number of B-O-B links and B-OH bonds present are, respectively

• five and four

• four and five

• three and four

• five and five

The stable bivalency of Pb and trivalency of Bi is

• due to d contraction in Pb and Bi

• due to relativistic contraction of the 6s orbitals of Pb and Bi, leading to inert pair effect

• due to screening effec

• due to attainment of noble liquid configuration

Which of the following is correct?

• Radius of Ca²⁺ <Cl^- < S^2-

• Radius of  <Cl^- < S^2- < Ca²⁺

• Radius of S^2-= Cl^-= Ca²⁺

• Radius of Ca²⁺ >Cl^- > S^2-

Which one of the following has the lowest ionisation energy?

• 1s², 2s², 2p⁶

• 1s², 2s², 2p⁶, 3s¹

• 1s², 2s², 2p⁵

• 1s², 2s², 2p³

207.

If the first ionization energy of H atom is 13.6 eV, then the second ionization energy of He atom is

• 27.2 eV

• 40.8 eV

• 54.4 eV

• 108.8 eV

How many unpaired electrons are present in Ni²⁺ cation? (Z = 28)

• 0

• 2

• 4

• 6

An oxide of a non-metal has the following properties

(i) It acts both as proton donor as well as proton acceptor

(ii) It reacts readily with basic and acidic oxides

(iii) It oxidies Fe at its boiling point. The oxide maybe

• P₂O₅

• SiO₂

• H₂O

• CO₂

Consider the following changes

M(s) → M(g)                ... (1)
M(g) → M²⁺(g) + 2e^-    ...(2)
Mg) → M⁺(g) + e^-         ...(3)
M(g) → M²⁺(g) + e^-      ...(4)
M(g) → M²⁺ (g) + 2e^-   ...(5)
The second ionisation energy of M could be determined from the energy values associated with 

• 1 + 2 + 4

• 2 + 3 - 4

• 1 + 5 - 3

• 5 - 3