If the half-life of uranium-235 is 704,000,000 years and 12.5 g of uranium-235 remains after 4,560,000,000 years, how much of the radioactive isotope was in the original sample?

May someone me with these science questions

Calculate the estimated density of each ball. use the formula d = m/v where d is the density, m is the mass, and v is the volume. record your calculations in table a of your student guide. given that the density of water is 1.0 g/cm3, make a prediction about whether each ball will float in water. record your prediction in table a. what is the estimated density of the table tennis ball? record your answer to the nearest hundredth

Which of the following is a possible formula unit? (2 points) select one: a. pbo b. li2b c. al2pb3 d. clo