Why are deposits of pure sodium metal or pure potassium metal not seen in nature

When a nucleus absorbs a neutron and then breaks apart, there are many products of the reaction. what is not a product of a nuclear fission reaction

Why is the melting of ice a physical change ?

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?