Air pressure is measured with a barometer.
(does this belong in chemistry?)
anyways, the parent was most likely a kid who wanted privacy. they wanted something so they are giving it to their kids.
Answer:
A. the atomic number
Explanation:
It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth.
Answer:
A. a system that can be affected by the outside environment, by an exchange of matter or energy