Chemistry JAMB Past Questions And Answers (Objectives and Theory)

 

Chemistry questions including both multiple-choice objectives and theory questions:

 

Section A: Multiple Choice Questions

 

Question: What is the chemical symbol for sodium?

 

A) So

B) Na

C) Sn

D) Sa

Answer: B) Na

Question: Which of the following is a noble gas?

 

A) Hydrogen

B) Oxygen

C) Helium

D) Nitrogen

Answer: C) Helium

Question: What is the pH value of a neutral solution?

 

A) 0

B) 7

C) 10

D) 14

Answer: B) 7

Question: What is the chemical formula for water?

 

A) H2O

B) CO2

C) NaCl

D) HCl

Answer: A) H2O

Question: What is the atomic number of oxygen?

 

A) 6

B) 8

C) 12

D) 16

Answer: B) 8

 

Section B: Theory Questions

 

Question: Define an element and provide an example.

 

Answer: An element is a pure substance composed of atoms that have the same number of protons in their atomic nuclei. Example: Oxygen (O).

Question: Explain the difference between an atom and a molecule.

 

Answer: An atom is the smallest unit of an element that retains its chemical properties. A molecule is a group of atoms bonded together, representing the smallest unit of a compound that retains its chemical properties.

Question: Describe the process of chemical bonding and provide examples of different types of chemical bonds.

 

Answer: Chemical bonding is the process by which atoms are held together to form compounds. Examples of different types of chemical bonds include:

Ionic bonds: Formed by the transfer of electrons from one atom to another, resulting in the attraction between oppositely charged ions (e.g., NaCl).

Covalent bonds: Formed by the sharing of electrons between atoms (e.g., H2O).

Metallic bonds: Formed by the delocalized electrons in a metal lattice (e.g., copper).

Question: Discuss the properties of acids and bases and provide examples of each.

 

Answer: Acids are substances that release hydrogen ions (H+) when dissolved in water, have a sour taste, and turn blue litmus paper red. Examples include hydrochloric acid (HCl) and sulfuric acid (H2SO4). Bases are substances that release hydroxide ions (OH-) when dissolved in water, have a bitter taste, and turn red litmus paper blue. Examples include sodium hydroxide (NaOH) and potassium hydroxide (KOH).

Question: Explain the difference between physical and chemical changes, providing examples of each.

 

Answer: Physical changes are changes that alter the form or appearance of a substance without changing its chemical composition. Examples include melting ice and boiling water. Chemical changes, on the other hand, result in the formation of new substances with different chemical properties. Examples include burning wood (formation of ash) and rusting of iron.