GED Science Physical Science 5 — Questions and Answers
Question 1: Which of the following best describes an endothermic reaction?
- A reaction that releases energy to the surroundings
- A reaction that absorbs energy from the surroundings (Correct answer)
- A reaction that occurs only at very high temperatures
- A reaction that produces an explosion
Correct answer: A reaction that absorbs energy from the surroundings
Endothermic reactions absorb heat from the surroundings, causing the environment to feel cooler.
Question 2: A student pushes a box across the floor with a force of 30 N and the box moves 4 meters. How much work is done?
- 7.5 J
- 34 J
- 120 J (Correct answer)
- 26 J
Correct answer: 120 J
Work = force × distance = 30 N × 4 m = 120 J.
Question 3: What happens to the density of most solids when they are heated?
- Density increases because the atoms vibrate faster
- Density stays the same because mass and volume both stay the same
- Density decreases because the volume increases while mass stays the same (Correct answer)
- Density increases because the particles pack more tightly
Correct answer: Density decreases because the volume increases while mass stays the same
Heating causes most solids to expand (increase in volume) while their mass stays constant, so density decreases.
Question 4: Which law states that the total momentum of a closed system remains constant if no external forces act on it?
- Newton's First Law
- Law of Conservation of Energy
- Law of Conservation of Momentum (Correct answer)
- Newton's Third Law
Correct answer: Law of Conservation of Momentum
The Law of Conservation of Momentum states that total momentum in a closed system is constant in the absence of external forces.
Question 5: A mixture of sand and iron filings can best be separated by using:
- Filtration
- Distillation
- A magnet (Correct answer)
- Evaporation
Correct answer: A magnet
Iron is magnetic and sand is not, so passing a magnet over the mixture will attract and separate the iron filings.
Question 6: Which of the following is true about isotopes of the same element?
- They have the same number of neutrons but different numbers of protons
- They have the same number of protons but different numbers of neutrons (Correct answer)
- They have different chemical properties from each other
- They have the same mass number but different atomic numbers
Correct answer: They have the same number of protons but different numbers of neutrons
Isotopes are atoms of the same element with the same number of protons but differing numbers of neutrons, giving them different mass numbers.
Question 7: A light ray passes from air into glass and bends toward the normal. This phenomenon is called:
- Reflection
- Diffraction
- Refraction (Correct answer)
- Absorption
Correct answer: Refraction
Refraction is the bending of light as it passes from one medium to another due to a change in its speed.
GED Science Physical Science 5
Which of the following best describes an endothermic reaction?