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?

According to the tide table below what time of day will the highest tide occur?

How many molecules are found in 1.32 mol of nacl?

A5.000 g sample of niso4 h2o decomposed to give 2.755 g of anhydrous niso4. what is the formula of the hydrate? what is the full chemical name for the hydrate? what is the molar mass of the hydrate? niso4•_h2o what is the mass % of water in the hydrate?