p-Block Elements — Page 6 | JEE Chemistry

Q51

Among the following oxoacids, the correct decreasing order of acid strength is :

A HClO4 > HClO3 > HClO2 > HOCl

B HClO2 > HClO4 > HClO3 > HOCl

C HOCl > HClO2 > HClO3 > HClO4

D HClO4 > HOCl > HClO3 > HClO2

Correct Answer

Option A

Solution

Acidic strength increases as the oxidation number of central atom increases. Hence acidic strength order is

\begin{aligned}& \left( { + 7} \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\left( { + 5} \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\left( { + 3} \right)\,\,\,\,\,\,\,\,\,\,\,\left( { + 3} \right) \\ & HCl{O_4}\, > \,HCl{O_3}\, > \,HCl{O_2}\, > \,HClO\end{aligned}

Q52

Which one of the following properties is not shown by NO?

A It combines with oxygen to form nitrogen dioxide

B It’s bond order is 2.5

C It is diamagnetic in gaseous state

D It is a neutral oxide

Correct Answer

Option C

Solution

Nitric oxide is paramagnetic in the gaseous state because of the presence of one unpaired electron in its outermost shell.

The electronic configuration of

NO

is

\sigma _{1s}^2\,\sigma _{1s}^{ * 2}\,\sigma _{2s}^2\,\sigma _{2s}^{ \circ 2}\,\sigma _{{2_{{p_z}}}}^2\,\pi _{{2_{{p_x}}}}^2

= \pi _{{2_{Py}}}^2\,\pi _{{2_{Px}}}^{ * 1}

Q53

The correct statement for the molecule, CsI3 is :

A it contains Cs3+ and I- ions.

B it contains Cs+, I- and lattice I2 molecule.

C it is a covalent molecule

D it contains Cs+ and

I_3^-

ions

Correct Answer

Option D

Solution

Cs{l_3}\,\,

dissociates as

Cs{l_3} \to C{s^ + } + I_3^ -

Q54

Which one has the highest boiling point?

A Ne

B Kr

C Xe

D He

Correct Answer

Option C

Solution

Xe.

As we move down the group, the melting and boiling points show a regular increase due to corresponding increase in the magnitude of their van der waal forces of attraction as the size of the atom increases.

Q55

Assertion : Nitrogen and Oxygen are the main components in the atmosphere but these do not react to form oxides of nitrogen. Reason : The reaction between nitrogen and oxygen requires high temperature.

A Both assertion and reason are correct, and the reason is the correct explanation for the assertion

B Both assertion and reason are correct, but the reason is not the correct explanation for the assertion

C The assertion is incorrect, but the reason is correct

D Both the assertion and reason are incorrect

Correct Answer

Option A

Solution

Nitrogen and oxygen in air do not react to form oxides of nitrogen in atmosphere because the reaction between nitrogen and oxygen requires high temperature.

Q56

Assertion : Among the carbon allotropes, diamond is an insulator, whereas, graphite is a good conductor of electricity. Reason : Hybridization of carbon in diamond and graphite are sp3 and sp2, respectively.

A Both assertion and reason are correct, and the reason is the correct explanation for the assertion.

B Both assertion and reason are correct, but the reason is not the correct explanation for the assertion

C Assertion is incorrect statement, but the reason is correct.

D Both assertion and reason are incorrect.

Correct Answer

Option B

Solution

In diamond, each C - atom is covalently bonded with four other carbon atom.

So it utilizes its four unpaired electrons in bond formation.

Due to this reason diamond is a bad conductor of electricity.

In graphite, each carbon atom is covalently bonded to three carbon atom.

In those bond formation 3 out of 4 valence electrons of each C - atom are used while the fourth electron is free to move in the structure of graphite.

Due to this reason graphite is a good conductor of electricity.

In diamond, each carbon is bonded with 4 other carbon so, carbon is sp3 hybridized.

In graphite, each carbon is bonded with 3 other carbon so carbon is sp2 hybridized.

So, here both Assertion and Reason are correct but hybridization is not the reason for the Assertion.

Q57

Aqueous solution of which salt will not contain ions with the electronic configuration 1s22s22p63s23p6 ?

A NaF

B NaCl

C KBr

D CaI2

Correct Answer

Option A

Solution

NaF is composed of Na+ and F–.

Na+ : 1s22s22p6 F- : 1s22s22p6 Hence do not match with the configuration given in the question.

Q58

The non-metal that does not exhibit positive oxidation state is :

A Oxygen

B Iodine

C Chlorine

D Fluorine

Correct Answer

Option D

Solution

Fluorine is the most electronegative element and it shows only –1 oxidation state.

Q59

Which intermolecular force is most responsible in allowing xenon gas to liquefy?

A Dipole - dipole

B Ion - dipole

C Instantaneous dipole - induced dipole

D Ionic

Correct Answer

Option C

Solution

Instantaneous dipole-induced dipole forces or van der Waals’ forces are most responsible in allowing xenon gas to liquify.

Q60

The number of S = O and S − OH bonds present in peroxodisulphuric acid and pyrosulphuric acid respectively are :

A (2 and 2) and (2 and 2)

B (2 and 4) and (2 and 4)

C (4 and 2) and (2 and 4)

D (4 and 2) and (4 and 2)

Correct Answer

Option D

Solution

Peroxidisulphuric Acid (H2 S2 O8) : Number of S = O, bonds = 4 Number of S $-$ OH, bond = 2 Pyrosulphuric Acid (H2 S2 O7) : Number of S = O, bonds = 4 Number of S $-$ OH, bonds = 2