The order of stability of metal oxides is

• Al₂O₃ < MgO < Fe₂O₃ < Cr₂O₃

• Cr₂O₃ < MgO < Al₂O₃ < Fe₂O₃

• Fe₂O₃ < Cr₂O₃ < Al₂O₃ < MgO

• Fe₂O₃ < Al₂O₃ < Cr₂O₃ < MgO

142.

Carbon can reduce ferric oxide to iron at a temperature above 983 K because

• carbon monoxide formed is thermodynamically less stable than ferric oxide

• carbon has a higher affinity towards oxidation than iron

• free energy change for the formation of carbon dioxide is less negative than that for ferric oxide

• iron has a higher affinity towards oxygen than carbon

Generally, the first ionisation energy increases along a period. But there are some exceptions. The one which is not an exception is

• Be and B

• Na and Mg

• Mg and Al

• N and O

Impossible orbital among the following is

• 3f

• 2p

• 4d

• 2s

The correct order of electronegativities of N, O, F and P is

• F > O > P > N

• F > O > N > P

• N > O > F > P

• F > N > P > O

The correct order of ionisation energy of C, N, O and F is

• C < N < O < F

• C < O < N < F

• F < O < N < C

• F < N < C < O

A metallic oxide reacts with water to from its hydroxide, hydrogen peroxide and also liberates oxygen. The metallic oxide could be

• CaO

• KO₂

• Li₂O

• Na₂O₂

Which one of these is not known?

• CuCl₂

• CuI₂

• CuF₂

• CuBr₂

The species that is not hydrolysed in water is

• P₄O₁₀

• BaO₂

• Mg₈N₂

• CaC₂

Pauling's electronegativity values for elements are useful in predicting :

• polarity of bonds in molecules

• position of elements in electromotive series

• co-ordination number

• dipole moment of various molecules