Practice Start Test

p-Block Elements

NEET Chemistry · 114 questions · Page 8 of 12 · Click an option or "Show Solution" to reveal answer

Q71
When copper is heated with conc. HNO 3 it produces
A Cu(NO 3 ) 2 , NO and NO 2
B Cu(NO 3 ) 2 and N 2 O
C Cu(NO 3 ) 2 and NO 2
D Cu(NO 3 ) 2 and NO
Correct Answer
Option C
Solution

Cu +4HNO 3 (conc.) →\to Cu(NO 3 ) 2 + 2NO 2 + 2H 2 O

Q72
The formation of the oxide ion, O 2−- (g) from oxygen atom requires first an exthermic and then an endothermic step as shown below: O (g) + e −- → \to O −- (g) ; Δ\Delta f H o = −-141 kJ mol −-1 O −- (g) + e −- → \to O 2−- (g) ; Δ\Delta f H o = +780 kJ mol −-1 Thus, process of formation of O 2−- is isoelectronic with neon. It is due to the fact that,
A O −- ion has comparatively smaller size than oxygen atom
B oxygen is more electronegative
C addition of electron in oxygen results in larger size of the ion
D electron repulsion outweighs the stability gained by achieving noble gas configuration.
Correct Answer
Option D
Solution

The process of formation of O 2– in gas phase is unfavourable even though O 2– is isoelectronic with neon because electron repulsion outweigh the stability gained by achieving noble gas configuration.

Q73
Strong reducing behavior of H 3 PO 2 is due to
A high electron gain enthalpy of phosphorus
B high oxidation state of phosphorus
C presence of two −-OH groups and one P−-H bond
D presence of one −-OH group and two P−-H bonds.
Correct Answer
Option D
Solution

All oxyacids of phosphorus which have P—H bonds act as strong reducing agents.

H 3 PO 2 has two P—H bonds hence, it acts as a strong reducing agent.

Q74
The variation of the boiling points of the hydrogen halides is in the order HF > HI > HBr > HCl. What explains the higher boiling point of hydrogen fluoride?
A There is strong hydrogen bonding between HF molecules.
B The bond energy of HF molecules is greater than in other hydrogen halides.
C The effect of nuclear shielding is much reduced in fluorine which polarises the HF molecule.
D The electronegativity of fluorine is much higher than for other elements in the group.
Correct Answer
Option A
Solution

HF forms strong intermolecular H-bonding due to high electronegativity of F.

Hence, the boiling point of HF is exceptionally high.

Boiling points of other hydrogen halides gradually increases from HCl to HI due to increase in the size of halogen atoms form Cl to I, which further increases the magnitude of van der Waal's forces.

Q75
The stability of +1 oxidation state among Al, Ga, In and Tl increases in the sequence
A Al < Ga < In < Tl
B Tl < In < Ga < Al
C In < Tl < Ga < Al
D Ga < In < Al < Tl
Correct Answer
Option A
Solution

The given elements belong to 13th group.

The elements mainly exhibit +3 and +1 oxidation states.

As we know, the stability of lower oxidation state i.e., +1 state, increases on moving down the group due to inert pair effect.

The, stability follows the order : Al < Ga < In < Tl

Q76
Nitrogen dioxide and sulphur dioxide have some properties in common . Which property is shown by one of these compounds , but not by the other?
A Is soluble in water.
B Is used as a food preservative.
C Forms 'acid-rain'.
D Is a reducing agent.
Correct Answer
Option B
Solution

SO 2 is widely used in food and drinks industries for its property as a preservative and antioxidant while NO 2 is not used as food preservative.

Q77
Acidity of diprotic acids in aqueous solutions increases in the order
A H 2 S < H 2 Se < H 2 Te
B H 2 Se < H 2 S < H 2 Te
C H 2 Te < H 2 S < H 2 Se
D H 2 Se < H 2 Te < H 2 S
Correct Answer
Option A
Solution

As the atomic size increases down the group the bond length increases and the bond strength decreases and the cleavage of E - H bond become easier thus, more will be the acidity.

Thus, order of acidity will be H 2 S << H 2 Se << H 2 Te

Q78
Which statement is wrong?
A Beryl is an example of cyclic silicate.
B Mg 2 SiO 4 is orthosilicate.
C Basic structural unit in silicates is the SiO 4 tetrahedron.
D Feldspars are not aluminosilicates.
Correct Answer
Option D
Solution

Feldspars are three dimensional aluminosilicates.

Q79
Which is the strongest acid in the following?
A HClO 4
B H 2 SO 3
C H 2 SO 4
D HClO 3
Correct Answer
Option A
Solution

HClO 4 with highest oxidation number and its conjugate base is resonance stabilised, hence it is most acidic.

Q80
Which of the following structure is similar to graphite?
A B 4 C
B B 2 H 6
C BN
D B
Correct Answer
Option C
Solution

Boron nitride (BN) is known as inorganic graphite.

The most stable form is hexagonal one.

It has layered structure similar to graphite.

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