In which of the following pairs of molecules/ions, the central atoms have sp² hybridization?

• NO₂^- and NH₃

• BF₃ and NO₂^-

• NH₂^- and H₂O

• NH₂^- and H₂O

If pH ofa saturated solution of Ba(OH)₂ is 12, the value of its K_sp is 

• 4.00 x 10^-6 M³

• 4.00 x 10^-7 M³

• 5.00 x 10^-6 M³

• 5.00 x 10^-6 M³

Which one of the following species does not exist under normal conditions?

• Be₂⁺

• Be₂

• B₂

• B₂

The number of atoms in 0.1 moles of a triatomic gas is (N_A = 6.02 x 10²³ mol^-1)

• 6.026 x 10²²

• 1.806 x 10²³

• 3.600 x 10²³

• 3.600 x 10²³

Which of the following represents the correct order of increasing electron gain enthalpy with negative sign for the elements O, S, F and Cl?

• Cl < F < O < S

• O < S < F< Cl

• F < S < O < Cl

• F < S < O < Cl

Standard entropies X₂, Y₂ and XY₂ are 60, 40 and 50 J K^-1 mol^-1 respectively for the reaction


equilibrium, the temperature should be

• 750 K

• 1000 K 

• 1250 K

• 1250 K

In which one of the following species the central atom has the type of hybridisation which si not the same as that present in the other three? 

• SF4

• I₃^-

• SbCl₅^2-

• SbCl₅^2-

The correct order of the decreasing ionic radii among the following isoelectronic species is

• Ca²⁺ > K⁺ >S^2- > Cl^-

• Cl^- > S^2- > Ca²⁺ > K⁺

• S^2- > Cl^- > K⁺ > Ca²⁺

• S^2- > Cl^- > K⁺ > Ca²⁺

9.

Which of the following pairs has the same size? 

• Fe²⁺ , Ni²⁺

• Zr⁴⁺, Ti⁴⁺

• Zr⁴⁺, Hf⁴⁺

• Zr⁴⁺, Hf⁴⁺

What is [H⁺] in mol/L of a solution that is 0.20 M in CH₃COONa and 0.10 M in CH₃COOH? 
(K_a for CH₃COOH = 1.8 x 10^-5 )

• 3.5 x 10^-4

• 1.1 x 10^-5

• 1.8 x 10^-5

• 1.8 x 10^-5