p-Block Elements Questions — JEE Chemistry

Q1

A metal (A) on heating in nitrogen gas gives compound B. B on treatment with H2O gives a colourless gas which when passed through CuSO4 solution gives a dark blue-violet coloured solution. A and B respectively, are :

A Na and NaNO3

B Na and Na3N

C Mg and Mg3N2

D Mg and Mg(NO3)2

Correct Answer

Option C

Solution

3Mg(A) + N2

\overset{\Delta}\longrightarrow

Mg3N2(B)

\overset{{6{H_2}O}}\longrightarrow

3Mg(OH)2 + 2NH3 (colourless gas) CuSO + 4NH3 $\to$ [Cu(NH3)4]SO4 (deep blue solution)

Q2

In the following reaction, products (A) and (B) respectively, are : NaOH + Cl2

\to

(A) + side products (hot and conc.) Ca(OH)2 + Cl2

\to

(B) + side products (dry)

A NaOCl and Ca(OCl)2

B NaClO3 and Ca(ClO3)2

C NaOCl and Ca(ClO3)2

D NaClO3 and Ca(OCl)2

Correct Answer

Option D

Solution

NaOH + Cl2 $\to$ NaClO3 (A) + 5NaCl + 3H2O Ca(OH)2 + Cl2 $\to$ Ca(OCl)2 (B) + CaCl2 + 2H2O

Q3

The species given below that does NOT show disproportionation reaction is :

A

BrO_4^ -

B

Br{O^ - }

C

BrO_2^ -

D

BrO_3^ -

Correct Answer

Option A

Solution

In BrO4- , Br is in maximum oxidation state (+7), Soit cannot oxidise further it only reduced hence it cannot show disproportionation reaction.

Q4

Chemical nature of the nitrogen oxide compound obtained from a reaction of concentrated nitric acid and P4O10 (in 4 : 1 ratio) is :

A acidic

B basic

C amphoteric

D neutral

Correct Answer

Option A

Solution

Chemical nature of the nitrogen pentaoxide compound obtained from a reaction of concentrated nitric acid and P4O10 (in 4 : 1 ratio) is acidic.

Chemical reaction is as follows $\therefore$ N2O5 is an acidic oxide.

Q5

'X' melts at low temperature and is a bad conductor of electricity in both liquid and solid state. X is :

A Mercury

B Carbon tetrachloride

C Zinc sulphide

D Silicon carbide

Correct Answer

Option B

Solution

The melting point of carbon tetrachloride is −22.92 oC.

CCl4 is nonpolar solid so does not conduct electricity in liquid & solid state.

Q6

White Phosphorus on reaction with concentrated NaOH solution in an inert atmosphere of CO2 gives phosphine and compound (X). (X) on acidification with HCl gives compound (Y). The basicity of compound (Y) is :

A 2

B 4

C 1

D 3

Correct Answer

Option C

Solution

Basicity of H3PO2 = 1

Q7

Which one of the following substances has the highest proton affinity?

A H2S

B NH3

C PH3

D H2O

Correct Answer

Option B

Solution

Among the given compounds, the

N{H_3}

is most basic. Hence has highest proton affinity.

Q8

Beryllium and aluminium exhibit many properties which are similar. But the two elements differ in :

A exhibiting maximum covalency in compound

B exhibiting amphoteric nature in their oxides

C forming covalent halides

D forming polymeric hydrides

Correct Answer

Option A

Solution

The maximum valency of beryllium is

+2

white that of aluminium is

+3.

Q9

Which one the following statement regarding helium is incorrect?

A It is used to fill gas balloons instead of hydrogen because it is lighter and non–inflammable

B It is used in gas – cooled nuclear reactors

C It is used to produce and sustain powerful superconducting reagents

D It is used as cryogenic agent for carrying out experiments at low temperatures

Correct Answer

Option A

Solution

Helium is heavier than hydrogen although it is non-inflammable

Q10

Which among the following factors is the most important in making fluorine the strongest oxidizing halogen?

A Electron affinity

B Bond dissociation energy

C Hydration enthalpy

D Ionization enthalpy

Correct Answer

Option B

Solution

The fluorine has low dissociation energy of

F

-

F

bond and reaction of atomic fluorine is exothermic in nature.