If we start with 48 atoms of a radioactive substance, how many would remain after one halflife? after two half-lives? after three half-lives? after four halflives? Please I need help now

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?

12. calculate the hydroxide ion concentration of a solution with ph = 3.25. show all calculations leading to an answer

What natural processes produce large quantities of co2