Which is the most thermodynamically stable form of carbon?

• Carbon black

• Graphene

• Graphite

• Diamond

The second ionisation enthalpies of Li, Be, B and C are in order

• Li > B > C > Be

• Li > C > B > Be

• Be > C > B > Li

• B > C > Be > Li

The ionic species having the largest size is

• Li⁺ (g)

• Rb⁺(aq)

• Li⁺(aq)

• Cs⁺(aq)

The first four ionisation enthalpy values of an element are 191 kcal mol^-1 578 kcal mol^-1 872 kcal mol^-1 and 5962 kcal mol^-1 .The number of valence electrons in the element is

• 1

• 2

• 3

• 4

The ion having the highest mobility in aqueous solution is

• Ba²⁺

• Mg²⁺

• Ca²⁺

• Be²⁺

Carborundum is the commercial name of

• B₄C

• SiO₂

• SiC

• Al₂O₃

Among the following alkenes, which one is ,the most stable?

• CH₂=CH₂

• CH₃-CH=CH₂

• CH3-CH=CH-CH₃

• (CH₃)₂C=C(CH₃)₂

18.

For a fuel cell, which statementis correct?

• Hydrogen is oxidised to H₂O at cathode

• Oxygen is reduced to OH^- at anode

• Hydrogen is oxidised to H₂O at anode

• Hydrogen is oxidised to H⁺ at anode

2 × 10^-5C charge on Zn²⁺  ions corresponds to

• 2 × 10^-5 mol of Zn²⁺ ions

• 6.22  × 10⁷ Zn²⁺ ions

• 0.64 mg of Zn²⁺ ions

• 1 × 10^-10 mol Zn²⁺ ions.

Which statement is true?

• The adsorption of H₂ by platinum black is known as sorption

• The adsorption of H₂ by charcoal is known as occlusion

• The adsorption of H₂ by platinum black is known as occlusion

• The absorption of H₂ by charcoal is known as chemisorption.