Element Z has a mass of 430g. Scientists determined it to have a ½ life of 5 years. How many grams of element Z will remain after 15 years?

What is the number of moles of chemical units represented by 9.03x10^24? and how do i show work? (dumb it down )

Ill give brainiestif one neutron initiates a fission event that produces two neutrons in the products, how many new reactions can now be initiated? if each of the neutrons produced in the first fission event then initiates a fission event that produces one neutron in the products, how many new reactions can now be initiated by each neutron? how many neutrons in total were produced by the two fission events described?

Astring vibrates with a frequency of 10 hz. why can't a person hear the sound waves produced by the vibrating string, no matter how large the amplitude of the waves? out! this is homework and due tomorrow! you so much!