question:
Why do mountain climbers at high elevations use oxygen tanks to help them breathe?

answer:
The atmosphere is less dense at higher elevations so there is less oxygen available.

question:
Which activity is an example of a chemical change?

answer:
burning wood to produce ashes

question:
In New York State, an observer will usually see the Sun rise in the

answer:
east

question:
A large cold front is moving past the school on a hot, humid summer day. Which best describes the type of weather as the cold front passes by?

answer:
A thunderstorm