Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

Complete the following reaction sequence.

\[\begin{array}{cc}
\ce{O}\phantom{...............................................}\\
||\phantom{...............................................}\\
\ce{CH3 - C - CH3 ->[(i) CH3MgBr][H2O] (A) ->[Na metal][Ether] (B) ->[CH3 - Br] (C)}
\end{array}\]

Assertion: Formaldehyde is a planar molecule.

Reason: It contains sp² hybridised carbon atom.

The reaction \[\ce{Ar\overset{+}{N2}Cl- ->[Cu/HCl] ArCl + N2 + CuCl}\] is anmed as ______.

Which of the following cannot be prepared by Sandmeyer’s reaction?

(i) Chlorobenzene

(ii) Bromobenzene

(iii) Iodobenzene

(iv) Fluorobenzene

Arrange the following compounds in increasing order of dipole moment.

\[\ce{CH3CH2CH3, CH3CH2NH2, CH3CH2OH}\]

Discuss briefly, giving an example in the given case and the role of coordination compounds in biological systems.

Give reasons to support the answer:

3-Hydroxy pentan-2-one shows positive Tollen’s test.

Account for the following:

Ti(IV) is more stable than the Ti (II) or Ti(III).

Differentiate between the following:

Multimolecular Colloid and Macromolecular colloid

Assertion (A) : Osmotic pressure is a colligative property.

Reason (R) : Osmotic pressure is proportional to the molality.

Write the structures of A, B and C in the following reaction:

Determine the osmotic pressure of a solution prepared by dissolving 2.32 × 10⁻² g of K₂SO₄ in 2L of solution at 25°C assuming that K₂SO₄ is completely dissociated.

(R = 0.082 L atm K⁻¹ mol, Molar mass K₂SO₄ = 174 g mol⁻¹)

Write the equation for the following:

Reaction of chlorobenzene with CH₃Cl/anhyd. AlCl₃.

Illustrate Sandmeyer's reaction with an equation.

Anisole undergoes bromination with bromine in ethanoic acid even in the absence of iron (III) bromide catalyst.

What is actinoid contraction?

What causes actinoid contraction?

What is meant by the chelate effect? Give an example.

What is meant by the chelate effect? Give an example.

What is meant by the chelate effect? Give an example.