Can a substance be cooled to a temperature below its freezing point

Write the chemical formula for a compound that is made of an element from group 1 and an element from group 17

Liquid from a brewery fermentation contains 10% ethanol and 90% water. part of the fermentation product (50,000 kg/h) is pumped to a distillation column on the factory site. under current operating conditions, a distillate of 45% ethanol and 55% water is produced from the top of the column at a rate of one-tenth that of the feed. what is the composition of the waste "bottoms" from the still?

If a sample of radioactive isotopes takes 600 minutes to decay from 400 grams to 50 grams, what is the half-life of the isotope?