On the main sequence, hot stars are generally than cool ones.
a. more massive and longer-lived
b. less massive and longer-lived
C. more massive and shorter-lived
d. less massive and longer-lived
e. more massive, but we don't know how long they live

The modern periodic table has groups.

If two atoms are bonded to a central atom with no lone pairs, how will they be arranged

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.