Which of the following is an advantage of using parallax rather than the doppler effect to determine star distance?
answer

the doppler effect can be used only for sounds in space.

parallax is more accurate for stars that are very far away.

doppler shift indicates only a change in location, not actual distance.

parallax is easier to use than doppler shift.

Doppler shift indicates only a change in location, not actual distance.

Explanation:

Doppler effect occurs for both light and sound. When there is relative motion between two the source and the observer, there is apparent shift in the observed frequency. A red shift in the spectrum of star indicates that it is moving away from us and a blue shift indicates that it is moving towards us. Doppler effect does not indicate the distance. It just tells the changing position of the star.

Parallax method is used to measure the distance of the star. It calculates the change in relative position of a star with respect to its  distant background. The angle is measured and this tells the distance to the star.

d) physical means can be used to separate the components of air.