A cold, irregularly shaped region in the interstellar medium that diminishes or completelyobscures the light from background stars is called a//an:
a) irregular galaxy
b) dark dust cloud
c) emission nebula
d) reflection nebula
e) planetary nebula
Ans: b) dark dust cloud
You might also like to view...
In an elastic collision between two bodies of equal mass, with body 2 initially at rest, body 1 moves off at angle ? relative to the direction of its initial velocity and body 2 at angle ?. The sine of the sum of ? and ?, sin(? + ?), is equal to
a. 0. b. 0.500. c. 0.707. d. 0.866. e. 1.00.
A waiter in a restaurant fills a pitcher full of water and ice so that water would spill out if any more were added. As the ice starts to melt
a. the water level in the pitcher falls. b. the water level in the pitcher remains the same. c. water starts to flow out the spout of the pitcher. d. the pressure on the bottom of the pitcher decreases. e. the pressure on the bottom of the pitcher increases.
One mole of helium gas expands adiabatically from 2 atm pressure to 1 atm pressure. If the original temperature of the gas is 20°C, what is the final temperature of the gas? (g = 1.67)
Approximately how many other planetary systems have been discovered to date?
A) tens B) hundreds C) thousands D) tens of thousands E) millions