21.

The $∆$H°_f for CO₂ (g), CO (g) and H₂O (g) are -393.5, -110.5 and -241.8 kJ/ mol respectively. The standard enthalpy change (in kJ) for the reaction-

CO₂ (g) + H₂ (g) → CO (g) + H₂O (g) is :

• 524.1

• 41.2

• -262.5

• -41.2

In the reaction,

R - C ≡N + 4(H) $\stackrel{\mathrm{X}}{\to }$ RCH₂NH₂

X can be

• LiAlH₄

• H₂SO₄

• Ni

• 2KBr

The compound having the lowest oxidation state of iron is :

• K₄Fe(CN)₆

• K₂FeO₄

• Fe₂O₃

• Fe(CO)₅

The IUPAC name of the compound CH₂CONHBr is :

• 1-bromoacetamide 

• ethanoyl bromide

• N-bromo ethanamide

• None of the above

Which of the following is a dynamic isomerism?

• Metamerism

• Geometrical isomerism

• Tautomerism

• Co-ordinate isomerism

When K₂Cr₂O₇ is converted into K₂CrO₄, the change in oxidation number of chromium is :

• 0

• 5

• 7

• 9

The reason for the loss of optical activity of lactic acid when OH group is changed by H is that:

• chiral centre of the molecule is destroyed

• molecules acquires asymmetry

• due to change in configuration

• structural changes occurs

Borax bead test of Cr (chromium) is :

• green

• blue

• violet

• brown

The IUPAC name of CH₃-CH₂-CHO is :

• propanal-1

• 2-methylbutanal

• butanal-1

• pentanal-1

The conditions for aromaticity is :

• molecule must have clouds of delocalised $\mathrm{\pi }$ electrons

• molecule must contain (4n + 2) $\mathrm{\pi }$ electrons

• both (a) and (b)

• None of the above