Atomic Structure & Periodic Table
Chemical Bonding & Structure
Acids, Bases & Salts
Organic Chemistry
Environmental Chemistry
100

True/False

All isotopes of an element have the same number of neutrons. 


False

Isotopes have the same number of protons but different numbers of neutrons, which gives them different mass numbers.

100

True/False

Ionic bonds form between two non-metals.

False

Ionic bonds form between a metal and a non-metal, where electrons are transferred. Two non-metals typically form covalent bonds.

100

True/False

All acids contain hydrogen ions in aqueous solution. 


True

Acids release H⁺ ions in water, which is the defining property of acids according to the Arrhenius theory.

100

True/False

Alkanes are unsaturated hydrocarbons.

False

Alkanes are saturated hydrocarbons — they contain only single bonds between carbon atoms. Unsaturated hydrocarbons (alkenes, alkynes) have double or triple bonds.

100

True/False

Carbon monoxide is harmless because it is colorless and odorless.

False

Carbon monoxide (CO) is dangerous precisely because it’s colorless and odorless. It binds to hemoglobin more strongly than oxygen, reducing oxygen transport in the body.

200

MCQ
Which subatomic particle determines the identity of an element?

A. Neutron 

B. Electron 

C. Proton 

D. Nucleon

C. Proton 

The number of protons (atomic number) defines the element. For example, carbon always has 6 protons.

200

MCQ 

Which of the following compounds contains covalent bonds? 

A. NaCl 

B. MgO 

C. CO₂ 

D. KBr

C. CO₂ 

Carbon dioxide (CO₂) is formed by sharing electrons between non-metals — a covalent bond.

200

MCQ 

Which of the following is a weak acid? 

A. HCl 

B. H₂SO₄ 

C. CH₃COOH 

D. HNO₃

C. CH₃COOH 

Acetic acid (CH₃COOH) only partially ionizes in water, making it a weak acid. The others are strong acids.

200

Fill in the Blanks

The functional group in alcohols is the ___ group. 

A. hydroxyl 

B. carboxyl 

C. alkyl 

D. amino

A. hydroxyl

Alcohols contain the hydroxyl group (-OH), which makes them polar and capable of hydrogen bonding.

200

MCQ
Which process removes carbon dioxide from the atmosphere?

A. Respiration 

B. Combustion 

C. Photosynthesis 

D. Fermentation

C. Photosynthesis 

Photosynthesis by plants absorbs CO₂ and releases oxygen, helping regulate atmospheric carbon.

300

Fill in the Blanks

The mass number of an atom is the sum of protons and ___. 

A. neutrons 

B. electrons

C. nucleons 

D. atoms

A. neutrons 

Mass number = protons + neutrons. Electrons have negligible mass.

300

Fill in the Blanks

In an ionic bond, electrons are ___ from one atom to another. 

A. transferred 

B. shared 

C. lost 

D. created

A. transferred 

Ionic bonding involves transfer of electrons from a metal to a non-metal, forming oppositely charged ions.

300

MCQ

Which salt is formed when hydrochloric acid reacts with sodium hydroxide?
A. Sodium chloride 

B. Sodium sulfate 

C. Sodium nitrate 

D. Sodium carbonate

A. Sodium chloride 

HCl + NaOH → NaCl + H₂O. This is a neutralization reaction.

300

MCQ 

Which compound is formed when ethanol is oxidized?

A. Ethene 

B. Ethanoic acid 

C. Methanol 

D. Propanol  

B. Ethanoic acid

Oxidation of ethanol (CH₃CH₂OH) produces ethanoic acid (CH₃COOH) — a carboxylic acid.

300

Fill in the Blanks

The greenhouse effect is caused by gases that trap ___ radiation.

A. infrared 

B. ultraviolet 

C. gamma 

D. visible  

A. infrared 

Infrared radiation is trapped by greenhouse gases like CO₂ and CH₄, warming the Earth’s surface.

400

MCQ

Which element is most reactive in Group I?
A. Lithium 

B. Sodium 

C. Potassium 

D. Cesium

D. Cesium

Cesium is the most reactive because reactivity increases down the group due to weaker attraction between nucleus and outer electron.

400

MCQ 

Which element is most likely to form a triple covalent bond?

A. Hydrogen 

B. Nitrogen 

C. Oxygen 

D. Fluorine  

B. Nitrogen 

Nitrogen has five valence electrons and often shares three pairs to complete its octet — forming a triple bond in N₂.

400

Fill in the Blanks

The pH scale ranges from ___ to 14. 

A. 0 

B. 1 

C. -1 

D. 2

A. 0 

The pH scale typically ranges from 0 (strong acid) to 14 (strong base).

400

Fill in the Blanks

The process of breaking down large hydrocarbons into smaller ones is called ___. 

A. cracking 

B. polymerization

C. combustion 

D. distillation


A. cracking 

Cracking breaks long-chain hydrocarbons into smaller, more useful molecules like alkenes and fuels.

400

True/False

Methane is less effective than carbon dioxide at trapping heat.

False

Methane (CH₄) is more potent than CO₂ in trapping heat, though it’s present in smaller quantities.

500

True/False

Noble gases are reactive because they have full outer shells.

False

Noble gases are unreactive because their outer shells are full — they are chemically stable.

500

True/False

Ionic compounds have low melting points due to weak electrostatic forces. 


False

Ionic compounds have high melting points because of strong electrostatic attraction between oppositely charged ions.

500

MCQ
Which of the following is an example of a basic oxide?

A. CO₂ 

B. Na₂O 

C. SO₂ 

D. NO₂

B. Na₂O 

Sodium oxide (Na₂O) reacts with water to form NaOH, a base — hence it’s a basic oxide.

500

Fill in the Blanks

The simplest alkane is ___, with the formula CH₄.

A. methane 

B. ethane 

C. propane 

D. butane  

A. methane

Methane is the simplest alkane — one carbon atom bonded to four hydrogen atoms.

500

MCQ
Which gas is primarily responsible for acid rain?

A. CO₂ 

B. SO₂ 

C. CH₄ 

D. O₂

B. SO₂ 

Sulfur dioxide (SO₂) reacts with water in the atmosphere to form sulfuric acid, contributing to acid rain.