Question
Which stages in the life cycle of a star are listed in the order that they occur?
A interstellar dust cloud \(\rightarrow\) stable star \(\rightarrow\) protostar
B protostar \(\rightarrow\) red giant \(\rightarrow\) stable star
C red giant \(\rightarrow\) white dwarf \(\rightarrow\) protostar
D stable star \(\rightarrow\) red giant \(\rightarrow\) white dwarf
▶️Answer/Explanation
Ans: D
Question
A planet orbits the Sun with orbital period \(T\). The average radius of the orbit is \(r\).
What is the average orbital speed of the planet?
A \(2 \pi r T\)
B \(\frac{2 \pi r}{T}\)
C \(\frac{T}{2 \pi r}\)
D \(\frac{\pi r}{2 T}\)
▶️Answer/Explanation
Ans:B
Question
The energy generated in stable stars comes from nuclear reactions.
Which type of reaction occurs in the Sun?
A Helium nuclei break up to give hydrogen nuclei.
B Helium nuclei join together to form hydrogen nuclei.
C Hydrogen nuclei break up to give helium nuclei.
D Hydrogen nuclei join together to form helium nuclei.
▶️Answer/Explanation
Ans:D