The half-life of isotope XX is 2.0 years. How many years would it take for a 7.0 mg sample of XX to decay and have only 0.4375 mg of it remain?

In a water molecule, hydrogen and oxygen are held together by a(an) bond. a) double covalent b) ionic c) nonpolar covalent d) hydrogen e) polar covalent

What type of matter is made of only one kind of atom

The density of the solid phase of a substance is 0.90 g/cm3 and the density of the liquid phase is 1.0 g/cm3. a large increase in pressure will a. lower the freezing point b. raise the freezing point c. lower the boiling point d. raise the triple point e. lower the triple point