Answer: Because it's a combination of chemicals, vodka doesn't freeze at the same temperature as either water or alcohol. Of course, vodka will freeze, but not at the temperature of an ordinary freezer. This is because vodka contains enough alcohol to lower the freezing point of water below the -17°C of your typical freezer.
Explanation: .......
It should remain constant because of the law of conservation of mass and because the flask is sealed no mass will escape
A homogeneous mixture, the substances are uniformly distributed throughout the mixture
The minerals in hard water react with soap and affect its cleaning capacity. It's still possible to use hard water when washing by using more soap. The additional soap will no longer be affected by the minerals in the water, so they can clean just as effectively, but you'll be wasting more soap this way.