Question 1

Which of the following represents the general valence shell electronic configuration for an element in Group 5 of the p-block?

Accepted Answer

ns²np³

Answer

ns²np²

Answer

ns²np⁵

Answer

np⁵

Question 2

What is the primary reason why Carbon (C) cannot undergo 'octet expansion' while Phosphorus (P) can?

Accepted Answer

Carbon lacks available d-orbitals in its second shell.

Answer

Carbon forms pπ-pπ multiple bonds which prevent expansion.

Answer

The C-C bond energy is too high to allow for extra bonds.

Answer

Carbon is more electronegative than Phosphorus.

Question 3

In the formation of the Al₂Cl₆ dimer, what type of bonding allows the aluminum atoms to achieve a full octet?

Accepted Answer

Coordinate covalent bonding

Answer

Ionic bonding

Answer

Hydrogen bonding

Answer

Metallic bonding

Question 4

Which statement accurately describes the structural difference between hexagonal boron nitride (BN) and graphite?

Accepted Answer

Atoms in adjoining layers of BN are positioned directly above one another, unlike in graphite.

Answer

The B-N bond is non-polar while the C-C bond is polar.

Answer

Graphite layers are held by covalent bonds while BN layers are held by ionic bonds.

Answer

BN contains delocalized electrons between layers while graphite does not.

Question 5

Why is hexagonal boron nitride an electrical insulator, whereas graphite is a conductor?

Accepted Answer

The electronegativity difference between B and N localizes the lone pair on the nitrogen atom.

Answer

BN has a diamond-like structure that prevents electron movement.

Answer

The layers in BN are too far apart for electrons to jump.

Answer

Boron nitride is an ionic compound.

Question 6

Which of the following reactions demonstrates the increasing stability of the +2 oxidation state in Group 4?

Accepted Answer

PbO₂ (s) + 4HCl (conc) arrow PbCl₂ (s) + Cl₂ (g) + 2H₂O (l)

Answer

CO₂ (g) + 2NaOH (aq) arrow Na₂CO₃ (aq) + H₂O (l)

Answer

CO (g) + CuO (s) arrow Cu (s) + CO₂ (g)

Answer

SiCl₄ (l) + 2H₂O (l) arrow SiO₂ (s) + 4HCl (g)

Question 7

When aqueous NaOH is added dropwise to a solution containing Pb²⁺ ions until in excess, what are the observed changes?

Accepted Answer

A white precipitate forms and then redissolves to give a colourless solution.

Answer

A dense white precipitate of PbCl₂ is formed immediately.

Answer

A yellow precipitate forms that is insoluble in excess alkali.

Answer

A white precipitate forms and remains unchanged in excess alkali.

Question 8

Why does CCl₄ not react with water, while SiCl₄ undergoes rapid hydrolysis?

Accepted Answer

Silicon has available 3d-orbitals to accept a lone pair from water, whereas carbon does not.

Answer

SiCl₄ is an ionic compound while CCl₄ is covalent.

Answer

The C-Cl bond is much stronger than the Si-Cl bond.

Answer

Carbon is too large for the water molecules to approach.

Question 9

In the reaction between chlorine and HOT concentrated sodium hydroxide, what are the oxidation states of chlorine in the products?

Accepted Answer

-1 and +5

Answer

0 and +1

Answer

+1 and +5

Answer

-1 and +1

Question 10

Which observations are associated with the reaction of concentrated sulfuric acid with sodium iodide (NaI)?

Accepted Answer

Purple fumes of I₂ and the smell of rotten eggs (H₂S).

Answer

Brown fumes of Br₂ and pungent SO₂.

Answer

A colourless solution of sodium iodate and water.

Answer

Steamy fumes of HCl only.

Question 11

What is the 'inert pair effect' as defined in the context of p-block chemistry?

Accepted Answer

The tendency of the outer s² pair of electrons to remain unshared in bonding.

Answer

The inability of Noble gases (Group 0) to react with other elements.

Answer

The shielding of inner electrons from the nuclear charge.

Answer

The tendency of p-block elements to form diatomic molecules like N₂.

Question 12

Which reagent is used to identify the presence of Pb²⁺ ions by forming a characteristic dense yellow precipitate?

Accepted Answer

Potassium iodide (KI)

Answer

Sodium hydroxide (NaOH)

Answer

Sulfuric acid (H₂SO₄)

Answer

Hydrochloric acid (HCl)

Question 13

In the context of Group 3 chemistry, why is a compound like BF₃ described as 'electron deficient'?

Accepted Answer

The central Boron atom has only six electrons in its valence shell.

Answer

Boron has a low electronegativity and loses its electrons to Fluorine.

Answer

There are no p electrons present in the Boron atom.

Answer

The compound is highly reactive with oxygen.

Question 14

Lead(II) oxide (PbO) reacts with both HNO₃ and NaOH. What term describes this behavior?

Accepted Answer

Amphoteric

Answer

Basic

Answer

Neutral

Answer

Disproportionation

Question 15

Which of the following is an industrial use for cubic boron nitride?

Accepted Answer

Industrial abrasive or wear-resistant coating

Answer

Lubricant in high-temperature environments

Answer

A substrate for semiconductors in electronics

Answer

Fuel source for rockets

Question 16

What happens to the oxidizing power of the halogens as you descend Group 7 from Chlorine to Iodine?

Accepted Answer

It decreases.

Answer

It decreases then increases.

Answer

It increases.

Answer

It remains constant.

Question 17

In the reaction Cl₂ + H₂O leftharpoons HCl + HOCl, the chlorine is said to have undergone...

Accepted Answer

Disproportionation

Answer

Thermal decomposition

Answer

Neutralization

Answer

Hydration only

Question 18

Why does HCl gas form when concentrated sulfuric acid is added to NaCl, but Cl₂ gas does not?

Accepted Answer

Chloride ions are not strong enough reducing agents to reduce sulfuric acid.

Answer

Chlorine is a gas and would escape the reaction mixture.

Answer

Sodium chloride is more stable than sodium bromide.

Answer

The reaction is conducted at too low a temperature.

Question 19

Which of the following describes the bonding in the adduct formed between NH₃ and BF₃?

Accepted Answer

A coordinate bond where Nitrogen donates a lone pair to Boron.

Answer

A metallic bond between the nitrogen and boron atoms.

Answer

An ionic bond formed by the transfer of an electron from Boron to Nitrogen.

Answer

A double bond between the Boron and Nitrogen atoms.

Question 20

What is the oxidation state of Phosphorus in PCl₅ and how is it possible given its group number?

Accepted Answer

+5; it is possible due to octet expansion using 3d orbitals.

Answer

+3; it only uses its p electrons for bonding.

Answer

+5; it is the only oxidation state available to Group 5 elements.

Answer

-5; it gains five electrons from the chlorine atoms.

Question 21

Which property of Carbon Monoxide (CO) is exploited in the extraction of iron from its oxide?

Accepted Answer

Its ability to act as a reducing agent.

Answer

Its ability to act as an oxidizing agent.

Answer

Its high solubility in molten iron.

Answer

Its acidic nature in aqueous solution.

Question 22

Carbon dioxide (CO₂) is a gas at room temperature while Lead(II) oxide (PbO) is a solid. What explains this difference?

Accepted Answer

CO₂ consists of small covalent molecules while PbO has a mainly ionic lattice structure.

Answer

Carbon dioxide is more chemically reactive than lead oxide.

Answer

CO₂ has giant covalent bonding while PbO is simple molecular.

Answer

Pb is a much heavier atom than C.

Question 23

In the reaction PbO + 2HNO₃ arrow Pb(NO₃)₂ + H₂O, Lead(II) oxide is acting as a...

Accepted Answer

Base

Answer

Catalyst

Answer

Acid

Answer

Reducing agent

Question 24

What happens to the Pb(OH)₂ precipitate when excess aqueous sodium hydroxide is added?

Accepted Answer

It redissolves to form the [Pb(OH)₄]²⁻ ion.

Answer

It turns into a yellow solid.

Answer

It decomposes into lead metal and oxygen gas.

Answer

It remains as a white solid.

Question 25

Bleaching by chlorine or chlorate(I) ions is fundamentally what type of chemical process?

Accepted Answer

Oxidation

Answer

Precipitation

Answer

Reduction

Answer

Neutralization

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