p-Block Elements — Page 9 | NEET Chemistry

Q81

Which of the following does not give oxygen on heating?

A K 2 Cr 2 O 7

B (NH 4 ) 2 Cr 2 O 7

C KClO 3

D Zn(ClO 3 ) 2

Correct Answer

Option B

Solution

(NH 4 ) 2 Cr 2 O 7

\overset{\Delta}\longrightarrow

N 2 + Cr 2 O 3 + 4H 2 O Zn(ClO 3 ) 2

\overset{\Delta}\longrightarrow

ZnCl 2 + 3O 2 KClO 3

\overset{\Delta}\longrightarrow

KCl +

{3 \over 2}

O 2 2K 2 Cr 2 O 7

\overset{\Delta}\longrightarrow

2K 2 CrO 4 + Cr 2 O 3 +

{3 \over 2}

O 2

Q82

Which one of the following molecules contains no

\pi

bond?

A SO 2

B NO 2

C CO 2

D H 2 O

Correct Answer

Option D

Solution

H 2 O does not contain any $\pi$ -bond.

Q83

The basic structural unit of silicates is

A SiO 3 2

-

B SiO

_4^{2 - }

C SiO

-

D SiO

_4^{4 - }

Correct Answer

Option D

Solution

SiO

_4^{4 - }

orthosilicate is basic unit of silicates.

Q84

Which of these is not a monomer for a high molecular mass silicone polymer?

A Me 3 SiCl

B PhSiCl 3

C MeSiCl 3

D Me 2 SiCl 2

Correct Answer

Option A

Solution

Since Me 3 SiCl contains only one Cl, therefore it can’t form high molecular mass silicon polymer.

It can form only dimer.

Q85

In which of the following arrangements the given sequence is not strictly according to the property indicated against it?

A HF < HCl < HBr < HI : increasing acidic strength

B H 2 O < H 2 S < H 2 Se < H 2 Te : increasing pK a values

C NH 3 < PH 3 < AsH 3 < SbH 3 : increasing acidic character

D CO 2 < SiO 2 < SnO 2 < PbO 2 : increasing oxidising power

Correct Answer

Option B

Solution

If acidic nature is high, K a is high and pK a is low. since pK a = – log K a Hence the order of pK a will be H 2 O > H 2 S > H 2 Se > H 2 Te

Q86

Sulphur trioxide can be obtained by which of the following reaction?

A CaSO 4 + C

\overset{\Delta}\longrightarrow

B Fe 2 (SO 4 ) 3

\overset{\Delta}\longrightarrow

C S + H 2 SO 4

\overset{\Delta}\longrightarrow

D H 2 SO 4 + PCl 5

\overset{\Delta}\longrightarrow

Correct Answer

Option B

Solution

Fe 2 (SO 4 ) 3

\overset{\Delta}\longrightarrow

Fe 2 O 3 + 3SO 3

Q87

In which of the following compounds, nitrogen exhibits highest oxidation state?

A N 2 H 4

B NH 3

C N 3 H

D NH 2 OH

Correct Answer

Option C

Solution

N 2 H 4 : Oxidation state of N = – 2 NH 3 : Oxidation state of N = – 3 N 3 H : Oxidation state of N = – 1/3 NH 2 OH : Oxidation state of N = – 1 $\therefore$ Highest oxidation state = –1/3

Q88

Which of the following statements is not valid for oxoacids of phosphorus?

A Orthophosphoric acid is used in the manufacture of triple superphosphate.

B Hypophosphorous acid is a diprotic acid.

C All oxoacids contain tetrahedral four coordinated phosphorus.

D All oxoacids contain atleast one P

=

O unit and one P

-

OH group.

Correct Answer

Option B

Solution

Hypophosphorus acid is a monoprotic acid.

Q89

Which of the following statements is incorrect?

A Pure sodium metal dissolves in liquid ammonia to give blue solution.

B NaOH reacts with glass to give sodium silicate.

C Aluminium reacts with excess NaOH to give Al(OH) 3 .

D NaHCO 3 on heating gives Na 2 CO 3 .

Correct Answer

Option C

Solution

Al reacts with NaOH to give sodium metaaluminate. 2Al(s) + 2NaOH (aq) + 2H 2 O(l) $\to$ 2NaAlO 2 + 3H 2

Q90

Which of the following oxide is amphoteric?

A SnO 2

B CaO

C SiO 2

D CO 2

Correct Answer

Option A

Solution

SnO 2 reacts with acid as well as base.

So SnO 2 is an amphoteric.

SnO 2 + 4HCl $\to$ SnCl 2 + 2H 2 O SnO 2 + 2NaOH $\to$ Na 2 SnO 3 + H 2 O CaO is basic in nature while SiO 2 and CO 2 are acidic in nature.