When does hydrogen first begin to fuse into helium in the star formation process?
A) when the cloud first begins to contract
B) when the thermal pressure is trapped at the center of the cloud
C) when the protostars undergoes convective contraction
D) when the protostar undergoes radiative contraction
E) only when the star reaches the main-sequence
Question 2The area in the Sun's atmosphere located above the chromosphere (1,500 - 10,000 km) where the temperature rises dramatically is called the
A) photosphere.
B) corona.
C) solar wind.
D) transition zone.
E) convection zone.
Question 3Unlike Earth, Mars' seasons are affected (enhanced and diminished) by the distance between Mars and the Sun. This is because:
A) Earth is closer to the Sun to begin with.
B) an Earth year is shorter.
C) Mars is tilted more on its axis than Earth is.
D) the orbit of Mars is significantly more elliptical.
E) Mars gets closer to the Sun than the Earth does.
Question 4In a hydrogen atom, a transition from the third to the second energy level will produce:
A) a red emission line.
B) a blue green absorption line.
C) a violet emission line.
D) an infrared emission line.
E) an ultraviolet absorption line.
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