My super brain

1.  9dimes-9pennies
2. 
   
3. Fill the 3 gallon jug full and pour it into the 5 gallon jug. Fill the 3 gallon jug full again and pour the other 2 gallons into the rest of the 5 gallon jug, leaving exactly 1 gallon left in the 3 gallon. Pour out the 5 gallon and pour the 1 gallon from the 3 gallon into the 5 gallon. Now fill up the 3 gallon full and pour into the 5 gallon jug leaving you with exactly 4 gallons.
4. July
5. Socks do not come in in left and right, so any black will pair with any other black and any white will pair with any other white. If you have three socks and they are either colored black or white, then you will have at least two socks of the same color, giving you one matching pair.
6. 28
7. If you ask one robot, " If I ask the other robot which door leads to freedom, what would he say?" (this is the question you should ask)
   If this robot you asked happens to be the truth teller, he would point the death door because he knew that the other robot, which is the liar, would lie.
   If this was the liar, he would lie and also point the death door.
   Either way, both would point the death door, so choose the other one.