DSST Physical Sciences 2 — Questions and Answers
Question 1: Which law states that the pressure of a gas is inversely proportional to its volume at constant temperature?
- Charles's Law
- Boyle's Law (Correct answer)
- Avogadro's Law
- Gay-Lussac's Law
Correct answer: Boyle's Law
Boyle's Law states that P × V = constant when temperature is held fixed.
Question 2: What type of radiation has the greatest penetrating power?
- Alpha particles
- Beta particles
- Gamma rays (Correct answer)
- Neutrons
Correct answer: Gamma rays
Gamma rays are high-energy electromagnetic radiation that can penetrate thick shielding materials.
Question 3: An object with a mass of 10 kg accelerates at 3 m/s². What is the net force acting on it?
- 3.3 N
- 13 N
- 30 N (Correct answer)
- 300 N
Correct answer: 30 N
Newton's second law: F = ma = 10 kg × 3 m/s² = 30 N.
Question 4: What is the oxidation state of sulfur in H₂SO₄?
- +2
- +4
- +6 (Correct answer)
- +8
Correct answer: +6
In H₂SO₄, hydrogen is +1 (×2) and oxygen is −2 (×4), so sulfur must be +6 to balance.
Question 5: Which phenomenon explains why the sky appears blue?
- Reflection
- Refraction
- Rayleigh scattering (Correct answer)
- Diffraction
Correct answer: Rayleigh scattering
Rayleigh scattering causes shorter (blue) wavelengths of sunlight to scatter more than longer wavelengths.
Question 6: What is the half-life of a radioactive isotope if 75% of a sample decays in 20 years?
- 5 years
- 10 years (Correct answer)
- 15 years
- 20 years
Correct answer: 10 years
75% decayed means 25% remains, which equals two half-lives (½ × ½ = ¼), so half-life = 20 ÷ 2 = 10 years.
Question 7: Which type of bond results from the electrostatic attraction between oppositely charged ions?
- Covalent bond
- Metallic bond
- Ionic bond (Correct answer)
- Hydrogen bond
Correct answer: Ionic bond
Ionic bonds form when electrons are transferred between atoms, creating oppositely charged ions that attract each other.
DSST Physical Sciences 2
Which law states that the pressure of a gas is inversely proportional to its volume at constant temperature?