Calculate the pOH of a solution at 25⁰C that contains 1 x 10^-10 M of hydronium ions.

• 7

• 4

• 9

• 9

A Weak acid, H_A has a K_a of 1.00 x 10^-5. If 0.100 mole of this percentage of acid dissociated at equilibrium is closest to:

• 99.0%

• 1.00%

• 99.9 %

• 99.9 %

Which of the following oxidation states are the most characteristics for lead and tin respectively? 

• +4,+2

• +2,+4

• +4,+4

• +4,+4

4.

The correct order of C-O bond length among CO, CO₃^2-, CO₂ is,

• CO₂<  CO₃^2-<  CO

• CO <  CO₃^2-<  CO₂

• CO₃^2- <CO₂ <CO

• CO₃^2- <CO₂ <CO

The following equilibrium constants are given:

N₂ + 3H₂  ⇌ 2NH₃; K₁

N₂ +O₂  ⇌ 2NO; K₂

H₂ + 1/2O₂  ⇌ H₂O' K₃

The equilibrium constants for the oxidation of NH₃ by oxygen to give NO is:

• K₂K₃³ /K₁

• KK₂K₃² /K₁

• K₂²K₃ /K₁

• K₂²K₃ /K₁

Consider the following sets of quantum numbers:

• ii, iii and iv

• i, ii, iii and iv

• ii, iv and v

• ii, iv and v

Consider the following reactions:


Enthalpy of formation of H₂O (l) is:

• - x₂ kJ mol^-1

• + x₃ kJ mol^-1

• - x₄ kJ mol^-1

• - x₄ kJ mol^-1

Given that bond energy of H-H and Cl- Cl are 430 kJ mol^-1 and 240 kJ mol^-1 respectively and ΔH_f for HCl is -90 kJ mol^-1. Bond and ΔH_f for HCl is -90 kJ mol^-1.Bond enthalpy of HCl is:

• 290 kJ mol^-1

• 380 kJ mol^-1

• 425 kJ mol^-1

• 425 kJ mol^-1

With which of the following electronic configuration an atom has the lowest ionisation enthalpy? 

• 1s² 2s²2p⁵

• 1s² 2s²2p³

• 1s² 2s²2p⁵ 3s¹

• 1s² 2s²2p⁵ 3s¹

An element, X has the following isotopic composition;


²⁰⁰X: 90%

¹⁹⁹X : 8.0%

²⁰²X ; 2.0 %

The weighted average atomic mass of the naturally -occurring element X is closet to:

• 200 amu

• 201 amu

• 202 amu

• 202 amu