DSST Physical Sciences 4 — Questions and Answers
Question 1: What is the net charge of a neutron?
- +1
- −1
- 0 (Correct answer)
- +2
Correct answer: 0
Neutrons are subatomic particles found in the nucleus with no electrical charge.
Question 2: According to the first law of thermodynamics, energy in a closed system is:
- Created during exothermic reactions
- Destroyed during endothermic reactions
- Conserved — neither created nor destroyed (Correct answer)
- Always converted to heat
Correct answer: Conserved — neither created nor destroyed
The first law of thermodynamics states that the total energy of an isolated system remains constant.
Question 3: What is the pH of a solution with a hydrogen ion concentration of 1 × 10⁻⁹ M?
- 5
- 7
- 9 (Correct answer)
- 11
Correct answer: 9
pH = −log[H⁺] = −log(10⁻⁹) = 9, indicating a basic solution.
Question 4: A projectile is launched horizontally from a cliff. Which component of its velocity remains constant (ignoring air resistance)?
- Vertical velocity
- Horizontal velocity (Correct answer)
- Both components
- Neither component
Correct answer: Horizontal velocity
Horizontal velocity remains constant because no horizontal force acts on the projectile during flight.
Question 5: Which electromagnetic waves have the shortest wavelengths?
- Radio waves
- Infrared waves
- X-rays
- Gamma rays (Correct answer)
Correct answer: Gamma rays
Gamma rays have the shortest wavelengths (less than 10⁻¹¹ m) and highest frequencies in the electromagnetic spectrum.
Question 6: What is Le Chatelier's Principle?
- Reactions always proceed to completion
- A system at equilibrium shifts to oppose a stress placed upon it (Correct answer)
- Temperature has no effect on equilibrium
- Catalysts shift equilibrium toward products
Correct answer: A system at equilibrium shifts to oppose a stress placed upon it
Le Chatelier's Principle states that a system at equilibrium will counteract any imposed change to restore balance.
Question 7: Two parallel wires carry current in the same direction. What is the magnetic force between them?
- Repulsive
- Attractive (Correct answer)
- Zero
- Alternating
Correct answer: Attractive
Parallel currents flowing in the same direction create magnetic fields that pull the wires toward each other.
DSST Physical Sciences 4
What is the net charge of a neutron?