To find the age of a cluster, astronomers must know:
A) the distance to the cluster.
B) the number of stars in the cluster.
C) the iron content of all the stars in the cluster.
D) the orbital motion of all the stars in the cluster.
A
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The crescent shapes of spots of light cast through openings in trees occurs with a
A) partial eclipse of the Sun. B) total eclipse of the Sun. C) lunar eclipse, partial or total. D) partial lunar eclipse.
Assuming that we can measure the apparent brightness of a star, what does the inverse square law for light allow us to do?
A) determine the distance to the star from its apparent brightness B) determine both the star's distance and luminosity from its apparent brightness C) calculate the star's surface temperature if we know either its luminosity or its distance D) calculate the star's luminosity if we know its distance, or calculate its distance if we know its luminosity
If you mix a typical iodine ion (I, atomic no. = 53) with a typical barium ion (Ba, atomic no. = 56), what compound is formed?
A) BaI2 B) BaI C) Ba56I53 D) Ba2I E) Ba2I2
Which of the following could be associated with a temperature increase for a fixed amount of gas?
1.a decrease in the volume at constant pressure 2.a decrease in the pressure at constant volume 3.a decrease in both the pressure and the volume 4.an increase in the pressure at constant volume