N-Level Combined Science 2 — Questions and Answers
Question 1: What is the process by which a liquid changes into a gas?
- Condensation
- Freezing
- Evaporation (Correct answer)
- Melting
Correct answer: Evaporation
Evaporation is the process by which a liquid changes into a gas at the surface of the liquid. It can occur at temperatures below the boiling point.
Question 2: What is an atom?
- The smallest part of an element that retains the chemical properties of that element (Correct answer)
- A molecule of water
- A type of chemical bond
- A charged particle
Correct answer: The smallest part of an element that retains the chemical properties of that element
An atom is the smallest unit of an element that retains the chemical properties of that element. It consists of protons, neutrons, and electrons.
Question 3: Which type of diet is essential for good health?
- A diet consisting only of protein
- A balanced diet with carbohydrates, proteins, fats, vitamins, minerals, and water (Correct answer)
- A diet with only fruits and vegetables
- A diet high in sugar and fat
Correct answer: A balanced diet with carbohydrates, proteins, fats, vitamins, minerals, and water
A balanced diet includes all essential nutrients in the right proportions: carbohydrates (energy), proteins (growth/repair), fats (energy store), vitamins and minerals (body functions), and water.
Question 4: What does a voltmeter measure?
- Current
- Resistance
- Voltage (potential difference) (Correct answer)
- Power
Correct answer: Voltage (potential difference)
A voltmeter measures the voltage (potential difference) across two points in a circuit. It is connected in parallel.
Question 5: What is the function of the lungs?
- To digest food
- To pump blood
- To exchange gases — absorbing oxygen and releasing carbon dioxide (Correct answer)
- To filter blood
Correct answer: To exchange gases — absorbing oxygen and releasing carbon dioxide
The lungs are the organs of gas exchange — oxygen from inhaled air enters the blood, and carbon dioxide from the blood is exhaled.
Question 6: What is friction?
- A pulling force
- A force that opposes motion between surfaces in contact (Correct answer)
- A force that pushes objects upward
- A magnetic force
Correct answer: A force that opposes motion between surfaces in contact
Friction is a force that opposes the relative motion of two surfaces in contact. It can be useful (preventing slipping) or a hindrance (reducing efficiency).
N-Level Combined Science 2
What is the process by which a liquid changes into a gas?