while preparing oxygen gas, the delivery tube is separated from the water trough before heating is stopped. why?

Using a value of ksp = 1.8 x 10-2 for the reaction pbcl2 pb+2(aq) + 2cl -(aq). if the value of ksp was determined to be only 1.2 x 10-2: too much solid has dissolved. additional precipitate is forming. the solution is unsaturated. the ions are now combining to reduce their concentrations.

Which rate indicates the number of children that would be born per woman if she were to live to the end of her child bearing years

What does a numerical subscript following an element in a chemical formula mean?