A 100.0 gram sample of water at 50.0oC is mixed with a 50.00 gram sample of water at 20.0oC. What is the final temperature of the 150.0 grams of water?

Iknow the answer is a but i don't know why

The formation of a solid, also known as a is an indication of a chemical change. precipitate particulate particle powder

If i initially have a gas at a pressure of 12 atm, a volume of 23 liters, and a temperature of 200 k, and then i raise the pressure to 14 atm and increase the temperature to 300 k, what is the new volume of the gas?