Stability of Stars

Q.

Light year is the unit of distance. It is the distance travelled by light in one year. If the speed of light is equal to $3\times {10}^8\raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$s$}\right.$ , how many kilo-meters will make up $1$ light year?

Q. A. if you are the sun, write about your properties in your own words.
B. Describe white dwarfs.

Q. Why is the distance between stars expressed in light years? What do you understand by the statement that a star is eight light years away from the Earth?

Q.

A star is a huge ball of glowing gas held together by gravity.

1. True
2. False

Q.

The heat and light energy is given out by our sun due to:

1. burning of the huge amounts of coal.

2. oxidation of hydrogen

3. fusion of hydrogen

4. none of the above.

Q. (a) Name a star of average brightness
(b) Why do stars appear as dim points in night sky

Q.

Light year is the unit of

1. time

2. distance

3. speed of light

4. none of these

Q.

The presence of bright sunlight :

1. keeps the Earth in its orbit

2. causes the different phases of moon to appear

3. makes the stars invisible during day time

4. causes the day/night cycle to occur

Q. The interval of time that elapses between two consecutive passages of a fixed star (other than the sun) across the meridian is called

1. mean solar year
2. mean solar day
3. mean sidereal day
4. mean sidereal year

Q. Which of the following lists contains ONLY heavy elements

1. Oxygen, Carbon, Iron
2. Helium, Oxygen, Carbon
3. Hydrogen, Helium, Carbon
4. Iron, Hydrogen, Oxygen

Q. The color of a star is determined by its temperature; the hottest stars are ________ and the coldest stars are ________ in color.

1. blue and white
2. white and red
3. blue and red
4. blue and yellow

Q. Do all the stars in the sky move? Explain.

Q. Analyzing the spectra of stars, the hottest stars are

1. red
2. orange
3. bluish white
4. there is no correlation between color and temperature

Q.

What is happening inside a star while it expands into a subgiant?

1. It is fusing hydrogen into helium in a shell outside the core.
2. It is fusing hydrogen into helium in the core.
3. It is fusing helium into carbon in a shell outside the core.
4. It is fusing helium into carbon in the core.

Q.

The distance of $1.8\times {10}^{7}km$ is equivalent to one light-year.

1. True
2. False

Q. Why do stars give out heat and light?

Q.

Which of the following statements about degeneracy pressure is not true?

1. Degeneracy pressure varies with the temperature of the star.
2. Degeneracy pressure can halt gravitational contraction of a star even when no fusion is occurring in the core.
3. Degeneracy pressure keeps any protostar less than 0.08 solar mass from becoming a true, hydrogen-fusing star.
4. Degeneracy pressure supports white dwarfs against gravity.

Q.

The source of the suns energy is the ____________.

Q. Why do massive stars have shorter lifespans than average stars?

1. They burn their fuel faster
2. They have less fuel to burn
3. They are excited to get through their lifecycles faster
4. They have less steps in their lifecycles

Q. Why do stars give out heat and light?