What are three ways to identify a substance?

Smell it, drink it, throw it at someone.

Explanation:

If none of that hurts or kills anyone, you can mark everything that would off the list.

Part 1:  0.5 mol

Part 2:  0.25 mol

Explanation:

For both problems, use the equation M = (moles of solute)/(liters of solvent).  

For part one, 1 M = (mol)/(0.5 L) = 0.5 mol.

For part two, 5 M = (mol)/(0.25 L) = 1.25 mol