Chemistry : The p-Block Elements

The charring of sugar takes place when treated with concentrated H₂SO₄. What is the type of reaction involved in it?

• Dehydration reaction

• Hydrolysis reaction

• Addition reaction

• Disproportionation reaction

The increasing order of the atomic radius of Si, S, Na, Mg, Al is

• S < Si< Al< Mg< Na

• Na< Mg < Si< Al< S

• Na< Mg< Si< Al < S

• Na< Mg< Al< Si< S

The molecular interactions responsible for hydrogen bonding in  HF

• ion-induced dipole

• dipole-dipole

• dipole- induced dipole

• ion-dipole

Assertion (A) : AlCl₃ exists as a dimer through halogen bridged bonds.

Reason (R) : AlCl₃ gets stability by accepting electrons from the bridged halogen.

• Both (A) and (R) are true and (R) is the correct explanation of (A).

• Both (A) and (R) are true but (R) is not the correct explanation of (A).

• (A) is true, but (H) is false.

• (A) is false, but (R) is true.

Which of the following statements regarding sulphur is not correct?

• At about 1000 K, it mainly consists of S, molecules.

• The oxidation state of sulphur is never less than + 4 in its compounds.

• S₂ molecule is paramagnetic.

• Rhombic sulphur is readily soluble in CS₂.

Which of the following forms holes in the ozone layer?

• CO

• SO₂

• CO₂

• CF₂Cl₂

To prepare XeF₆. Xe and F₂ are mixed at 573 K and 60-70 bar in the ratio of

• 20:1

• 1:5

• 5:1

• 1:20

In which of the following reactions, hydrogen is liberated?

$$\begin{gathered} \left(\mathrm{i}\right) \mathrm{Al}\left(\mathrm{s}\right) + \mathrm{HCl}\left(\mathrm{aq}\right) \to \\ \left(\mathrm{ii}\right) \mathrm{Al} \left(\mathrm{s}\right) +\hspace{0.17em}\mathrm{NaOH}\left(\mathrm{aq}\right)\hspace{0.17em}\to \\ \left(\mathrm{iii}\right) {\mathrm{NaBH}}_4 + {\mathrm{I}}_2 \to \end{gathered}$$

• i, ii

• ii, iii

• i,iii

• i, ii, iii

Two oxides of an non-metal X contain 50% and 40% of non-metal respectively. If the formula of the first oxide is XO₂. Then the formula of second oxide is

• X₂O₃

• X₂O₅

• XO₃

• X₂O

S + Conc. H₂SO₄ → X + Y 

Here X is a gas and Y is a liquid and both are triatomic molecules. The number of electron lone pairs present on the central atoms of X and Y are respectively.

• 2,1

• 1,0

• 1,2

• 2,2