GCSE Chemistry 2 — Questions and Answers
Question 1: Which type of bonding involves the sharing of electrons between two non-metal atoms?
- Ionic bonding
- Covalent bonding (Correct answer)
- Metallic bonding
- Hydrogen bonding
Correct answer: Covalent bonding
Covalent bonding occurs when two non-metal atoms share pairs of electrons to achieve stable electron configurations.
Question 2: What is the chemical formula for sulfuric acid?
- HCl
- HNO3
- H2SO4 (Correct answer)
- H3PO4
Correct answer: H2SO4
Sulfuric acid has the formula H2SO4, containing two hydrogen atoms, one sulfur atom, and four oxygen atoms.
Question 3: During electrolysis of brine (sodium chloride solution), what is produced at the cathode?
- Chlorine gas
- Oxygen gas
- Hydrogen gas (Correct answer)
- Sodium metal
Correct answer: Hydrogen gas
At the cathode (negative electrode), hydrogen ions from water are discharged, producing hydrogen gas.
Question 4: Which of the following is an example of an exothermic reaction?
- Photosynthesis
- Thermal decomposition of calcium carbonate
- Combustion of methane (Correct answer)
- Dissolving ammonium nitrate in water
Correct answer: Combustion of methane
Combustion of methane releases energy to the surroundings, making it an exothermic reaction.
Question 5: What does the term 'mole' represent in chemistry?
- 6.02 × 10²³ particles (Correct answer)
- The mass of one atom in grams
- The number of protons in an element
- The volume of one liter of gas
Correct answer: 6.02 × 10²³ particles
One mole contains 6.02 × 10²³ particles (Avogadro's number), allowing chemists to count atoms and molecules by mass.
Question 6: Which gas is produced when a metal carbonate reacts with a dilute acid?
- Hydrogen
- Oxygen
- Carbon dioxide (Correct answer)
- Nitrogen
Correct answer: Carbon dioxide
Metal carbonates react with acids to produce a salt, water, and carbon dioxide gas.
Question 7: What is the oxidation state of nitrogen in NH3?
- +3
- −3 (Correct answer)
- 0
- +1
Correct answer: −3
In NH3, hydrogen has an oxidation state of +1, so nitrogen must be −3 to give an overall charge of zero.
GCSE Chemistry 2
Which type of bonding involves the sharing of electrons between two non-metal atoms?