CSS - PMS - CCE - PCS - General Science
Black Holes
What radiation is theoretically emitted by black holes due to quantum effects near the horizon?
A. Hawking radiation
B. Visible light from a solid surface
C. Sound waves
D. Gamma rays from combustion
Correct Answer: A
Hawking's calculation predicts thermal radiation from quantum effects near black-hole horizons.
CSS - PMS - CCE - PCS - General Science
Black Holes
What is commonly found at the centers of many large galaxies?
A. Only neutron-free stars
B. Supermassive black holes
C. Only gas giants
D. Only comets
Correct Answer: B
Observations indicate supermassive black holes reside in many galactic nuclei.
CSS - PMS - CCE - PCS - General Science
Black Holes
What is a stellar-mass black hole usually formed from?
A. Freezing of a planet
B. Evaporation of an ocean
C. Collapse of a sufficiently massive star
D. Collision of two comets only
Correct Answer: C
Massive stellar cores can collapse after nuclear fuel is exhausted.
CSS - PMS - CCE - PCS - General Science
Black Holes
What is the Schwarzschild radius associated with?
A. The wavelength of sound
B. The size of an electron
C. The radius of Earth
D. The event-horizon radius of a non-rotating uncharged black hole
Correct Answer: D
For a non-rotating uncharged black hole, the Schwarzschild radius marks the event horizon.
CSS - PMS - CCE - PCS - General Science
Black Holes
What is the event horizon of a black hole?
A. The center of every galaxy
B. A visible solid surface
C. The boundary beyond which escape is impossible
D. A ring of planets
Correct Answer: C
The event horizon is a causal boundary, not a material surface.
CSS - PMS - CCE - PCS - General Science
Black Holes
What is a black hole?
A. A cold dark planet
B. A region of spacetime where gravity is so strong that nothing inside the event horizon can escape
C. A cloud made only of dust
D. A star with no gravity
Correct Answer: B
A black hole's defining feature is an event horizon beyond which escape to the outside is impossible.