Question 1

A protostar is a concentrated accumulation of gas and dust in outer space that will become a star.

Accepted Answer

A protostar is indeed a concentrated accumulation of gas and dust in outer space, representing an early stage in the formation of a star, before nuclear fusion has begun.

Question 2

The larger the apparent magnitude number, the brighter the star appears.

Accepted Answer

The apparent magnitude scale is inversely related to brightness: the larger the number, the dimmer the star appears.

Question 3

The absolute magnitude represents the brightness a star would appear from a standard distance of 32.6 light-years.

Accepted Answer

Absolute magnitude is a measure of the intrinsic brightness of a celestial object, such as a star, if it were placed at a standard distance of 10 parsecs, which is equivalent to approximately 32.6 light-years.

Question 4

The Sun's position at noon is best marked by the

Accepted Answer

The Sun's position at noon is best marked by the celestial meridian, which is an imaginary line in the sky that runs from the north point on the horizon, through the point directly overhead, to the south point on the horizon. This is the line the Sun crosses at local noon.

Question 5

Which of the following is evidence for the existence of "dark matter" in the universe?

Accepted Answer

The rotation curves of galaxies, which show the velocity of stars orbiting the galaxy's center, do not decrease as expected with distance from the center. Instead, stars at the outer edges of galaxies move faster than can be accounted for by the visible matter alone, suggesting the presence of additional, unseen mass, known as dark matter.

Question 6

When  undergoes beta-decay, the product is  .

Accepted Answer

The answer of When  undergoes beta-decay, the product is...

Question 7

If atom X undergoes radioactive decay and becomes atom Y with a half-life of five minutes. After 10 minutes, all number of X atoms have completely turned into to Y atoms.

Accepted Answer

The half-life concept means that after 5 minutes, only half of the X atoms would have decayed into Y atoms. After another 5 minutes (totaling 10 minutes), only half of the remaining X atoms would decay, leaving 25% of the original X atoms.

Question 8

This type of radiation is released when  .

Accepted Answer

The answer of This type of radiation is released when...

Question 9

Which of the following correctly balances this decay reaction?

Accepted Answer

The answer of Which of the following correctly balances this...

Question 10

Which of the following correctly balances this nuclear fission reaction?

Accepted Answer