21.

Assertion : Entropy is always constant for a closed system.

Reason : Closed system is always reversible.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

The compound which does not exist as hydrate form

• ferrous sulphate

• copper sulphate

• magnesium sulphate

• sodium chloride

Iodine oxidises sodium borohydride to give

• B₂H₆

• sodium hydride

• HI

• I₃^-

The wrong statement about fullerene is

• it has 5-membered carbon ring

• it has 6-membered carbon ring

• it has sp² hybridization

• it has 5-membered rings more than 6-membered rings

When KMnO₄ reacts with KBr in alkaline medium gives bromate ion. Then oxidation state of Mn changes from +7 to

• +6

• +4

• +3

• +2

How much amount of CuSO₄.5H₂O is required for liberation of 2.54 g of I₂ when titrated with KI?

• 2.5 gm

• 4.99 gm

• 2.4 gm

• 1.2 gm

Which material is used as a neutron moderator?

• Graphite

• Cadmium

• Boron

• Uranium

Decreasing order of nucleophilicity is

• OH^- > NH${}_2^{-}$ > CH₃O^- > RNH₂

• NH_{${}_2^{-}$} > OH^- > CH₃O^- > RNH₂

• NH_{${}_2^{-}$} > CH₃O^- > OH^- > RNH₂

• CH₃O^- > NH_{${}_2^{-}$} > OH^- > RNH₂

Find the number of stereoisomers of 1,2-dihydroxy cyclopentane.

• 1

• 2

• 3

• 4

Best method to form aromatic iodide is

• ArN${}_2^{+}$ + KI $\to$

• RNH₂ + I₂ $\to$

• ArN${}_2^{+}$ + KI $\to$

• ArN${}_2^{+}$ + PI₃ $\to$