p-Block Elements — Page 5 | JEE Chemistry

Q41

Identify the incorrect statement among the following :

A Ozone reacts with SO2 to give SO3

B Silicon reacts with NaOH(aq) in the presence of air to give Na2SiO3 and H2O

C Cl2 reacts with excess of NH3 to give N2 and HCl

D Br2 reacts with hot and strong NaOH solution to give NaBr, NaBrO4 and H2O

Correct Answer

Option D

Solution

To identify the incorrect statement among the given options, let's analyze each one : Option A : Ozone reacts with SO₂ to give SO₃.

Ozone (O₃) can react with sulfur dioxide (SO₂) to form sulfur trioxide (SO₃).

This reaction is a part of the atmospheric chemistry where ozone acts as an oxidizing agent.

Option B : Silicon reacts with NaOH(aq) in the presence of air to give Na₂SiO₃ and H₂O.

Silicon reacts with sodium hydroxide (NaOH) in the presence of air (oxygen) to form sodium silicate (Na₂SiO₃) and water (H₂O).

This reaction is feasible as silicon can be oxidized and dissolved by NaOH, especially in the presence of oxygen.

Option C : Cl₂ reacts with excess of NH₃ to give N₂ and HCl.

When chlorine (Cl₂) reacts with an excess of ammonia (NH₃), the main products are nitrogen (N₂) and hydrogen chloride (HCl).

This reaction is a well-known example of a redox reaction where chlorine is reduced and ammonia is oxidized.

Option D : Br₂ reacts with hot and strong NaOH solution to give NaBr, NaBrO₄, and H₂O.

Bromine (Br₂) reacts with hot and concentrated sodium hydroxide (NaOH) to form sodium bromide (NaBr), sodium bromate (NaBrO₃), and water (H₂O).

The formation of sodium perbromate (NaBrO₄) is not typical in this reaction under normal conditions.

Usually, NaBr and NaBrO₃ are the primary products.

Based on this analysis, the incorrect statement is Option D.

The expected products of the reaction between Br₂ and hot, concentrated NaOH are NaBr and NaBrO₃, not NaBr, NaBrO₄, and H₂O.

Q42

Al2O3 was leached with alkali to get X. The solution of X on passing of gas Y, forms Z. X, Y and Z respectively are :

A X = Na[Al(OH)4], Y = CO2, Z = Al2O3.xH2O

B X = Al(OH)3, Y = CO2, Z = Al2O3

C X = Al(OH)3, Y = SO2, Z = Al2O3.xH2O

D X = Na[Al(OH)4], Y = SO2, Z = Al2O3

Correct Answer

Option A

Solution

Al2O3 (aluminium oxide) was leached with alkali to get Na[Al(OH)4] (X) (sodium aluminate).

The solution of sodium aluminate when passed through gas Y, i.e. carbon dioxide (CO2) forms Al2O3.xH2O (Z).

Complete reactions are as follows

Q43

The stability of dihalides of

Si,Ge,Sn

and

Pb

increases steadily in the sequence :

A

Pb{X_2} < < Sn{X_2} < < Ge{X_2} < < Si{X_2}

B

Ge{X_2} < < Si{X_2} < < Sn{X_2} < < Pb{X_2}

C

Si{X_2} < < Ge{X_2} < < Pb{X_2} < < Sn{X_2}

D

Si{X_2} < < Ge{X_2} < < Sn{X_2} < < Pb{X_2}

Correct Answer

Option D

Solution

Reductance of valence shell electrons to participate in bonding is called inert pair effect.

The stability of lower oxidation state (

{ + 2\,\,}

for group

14

element) increases on going down the group. So the correct order is

Si{X_2} < Ge{X_2} < Sn{X_2} < Pb{X_2}

Q44

Which one of the following is the correct statement?

A Boric acid is a protonic acid

B Beryllium exhibits coordination number of six

C Chlorides of both beryllium and aluminium have bridged chloride structures in solid phase

D B2H6.2NH3 is known as ‘inorganic benzene’

Correct Answer

Option C

Solution

The coordination number exhibited by beryllium is

4

and not

6

so statement

(b)

is incorrect. Both

BeC{l_2}

and

AlC{l_3}

exhibit bridged structures is solid state so

(c)

is correct statement.

Q45

Among the following substituted silanes the one which will give rise to cross linked silicone polymer on hydrolysis is :

A R4Si

B RSiCl3

C R2SiCl2

D R3SiCl

Correct Answer

Option B

Solution

The cross linked polymers will be formed by

RSiC{l_3}

The correct choice is

(b)

Q46

Identify the incorrect statement :

A S2 is paramagnetic like oxygen.

B Rhombic and monoclinic sulphur have S8 molecules.

C S8 ring has a crown shape.

D The S-S-S bond angles in the S8 and S6 rings are the same.

Correct Answer

Option D

Solution

S8 ring has crown shape and bond angle is 107o S6 ring has chair form hexagon ring and bond angle is 102.2o.

Q47

Which one of the following reactions of Xenon compounds is not feasible?

A XeO3 + 6HF

\to

XeF6 + 3H2O

B XeF6 + RbF

\to

Rb(XeF7]

C 2XeF2 + 2H2O

\to

2Xe + 4HF + O2

D 3XeF4 + 6H2O

\to

2Xe + XeO3 + 12HF + 1.5O2

Correct Answer

Option A

Solution

To determine which of the given reactions of Xenon compounds is not feasible, we can analyze each option based on the chemical properties and reactivity of the substances involved : Option A :

\text{XeO}_3 + 6\text{HF} \to \text{XeF}_6 + 3\text{H}_2\text{O}

This reaction involves the conversion of xenon trioxide to xenon hexafluoride.

While both compounds are known, the direct conversion of XeO₃ to XeF₆ is not typically feasible due to the different oxidation states of xenon in these compounds and the reaction conditions required.

Option B :

\text{XeF}_6 + \text{RbF} \to \text{Rb}[\text{XeF}_7]

This reaction represents the formation of a rubidium heptafluoroxenate(VII) compound.

XeF₆ can react with RbF to form Rb[XeF₇], which is a known compound.

This reaction is feasible.

Option C :

2\text{XeF}_2 + 2\text{H}_2\text{O} \to 2\text{Xe} + 4\text{HF} + \text{O}_2

In this reaction, xenon difluoride is reacting with water to produce xenon, hydrofluoric acid, and oxygen.

XeF₂ is known to hydrolyze in the presence of water to produce these products, making this reaction feasible.

Option D :

3\text{XeF}_4 + 6\text{H}_2\text{O} \to 2\text{Xe} + \text{XeO}_3 + 12\text{HF} + 1.5\text{O}_2

This reaction suggests that xenon tetrafluoride reacts with water to form xenon, xenon trioxide, hydrofluoric acid, and oxygen.

The formation of XeO₃ and O₂ in this reaction is feasible as XeF₄ can undergo hydrolysis under certain conditions.

Given these considerations, Option A is the least feasible reaction among the ones listed.

The direct conversion of XeO₃ to XeF₆ is not commonly reported or expected under normal chemical reaction conditions.

Q48

Which of the following statement is wrong?

A Nitrogen cannot form

d\pi - p\pi

bond.

B Single N – N bond is weaker than the single P – P bond

C N2O4 has two resonance structures

D The stability of hydrides increases from NH3 to BiH3 in group 15 of the periodic table

Correct Answer

Option D

Solution

The case of formation and stability of hydrides decreases rapidly from

N{H_3}

to

Bi{H_3}.

. This is evident from their dissociation temperature which decreases from

N{H_3}

to

B{H_3}.

As we go down the group the size of central atom increases and thus metal-hydrogen bond becomes weaker due to decreased overlap between the large central atom and small hydrogen atom.

\mathop {N{H_3} > }\limits_{(most\,\,stable)} P{H_3} > As{H_3} > Sb{H_3}\mathop { > Bi{H_3}}\limits_{(least\,stable)}

Q49

Boron cannot form which one of the following anions?

A

BH_4^-

B

BF_6^{3-}

C

B(OH)_4^-

D

BO_2^-

Correct Answer

Option B

Solution

Boron cannot form

BF_6^{3 - }

due to non-availability of

d

-orbitals.

Q50

The molecule having smallest bond angle is :

A NCl3

B AsCl3

C SbCl3

D PCl3

Correct Answer

Option C

Solution

All the members form volatile halides of the type

A{X_3}.

All halides are pyramidal in shape.

The bond angle decreases on moving down the group due to decrease in bond pair-bond pair repulsion.

\begin{aligned}& NC{L_3}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,PC{l_3}\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,AsC{l^3} \\ & {107^ \circ }\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{94^ \circ }\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{92^ \circ }\end{aligned}