Science Buddies: "Ask an Expert"

I have some questions I would like to know the answers to. Just tell me the answers, the whole working is not needed.
Here I go:

The density of O2 (oxygen) is maximum at:
a) STP b) 273 K and 2 atm c) 546K and 1 atm d) 546K and 2 atm

Arrange the following in order of increasing mass:
a) 1 molecule of chlorine b) 1 atom of phosphorus c) 1 mole of CO2 d) 1 x {10 (to the power -10)} gm of copper

A motor boat of mass m moves along a lake with velocity v0. At t=0 the engine of the boat is shut down.. Resistive force offered to the boat is equal to k x {v (to the power 2)} where k is a constant. Then distance covered by the boat when its velocity becomes v0/2 is:
a) 3mv0/2k b) V0mln2/2k c) 2mln2/k d) mln2/k

x-1 / x(to the power 2) (x + 1) (x-2) > 0

Then x belongs to: (-infinity, 0) U (0,,2) U (2, infinity)
True or false?

Thank you!

These questions sound like homework. Science buddies ask the expert forum is intended to help with Science Fair projects.

1) Look up Reynolds Equation and/or Ideal gas law to understand how to figure out your first question.
2) The periodic table has the molecular weight for a mole of each atom. For compounds, you add the weights of all atoms in the formula. Avogadro's constant is the number of atoms in a mole. Combine all of this to figure out your second question.
3) If you have had calculus, this is straight forward. If not, you will have to look up some general solutions to time, distance, velocity problems.
4) Your last problem is a math problem. Read up on limits and roots.