Stars spend most of their lives
A) fusing hydrogen into helium in their cores
B) slowly dimming as they die with no fusion occurring in their cores
C) as slowly brightening protostars
D) fusing helium into carbon in their cores
A
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Temperature in the air is decreased by the process of.
In order to reduce bias, scientists usually prefer experiments that lead to what kind of results?
a. ambiguous b. imprecise c. quantitative d. qualitative e. subjective
Talk about vertigo! You've been dropped at the edge of a cliff, looking down for what seems to be miles! There's only one way to go from here: up! But it's going to be quite a climb, requiring all of the mountaineering skills you've ever heard of
The atmosphere here is very thin even at the mean surface level of this place; at altitude you'll never get a lungful. No matter, though; you could not breathe this atmosphere anyway, since it contains no oxygen; it's mostly carbon dioxide. You climb and climb; this mountain must be three times the height of Everest, and much broader at its base! There are clouds around you, and you can find water ice as well. When you try to melt it, however, it does not turn to liquid (it vaporizes to gas). Oh well, just keep climbing. But what will you do when you get to the top?
Galileo challenged the idea that objects in the heavens were perfect by ________
A) observing sunspots on the Sun and mountains on the Moon B) inventing the telescope C) proving Kepler's laws were correct D) showing that heavy objects fall at the same rate as lighter objects