The ratio of parent to daughter isotopes in a radioactive decay process is 0.40. How many half-lives have elapsed since the material was 100% parent atoms? A Between 2 and 3
B More than 3
C Between 1 and 2
D Less than 1

Aflashlight produces light using energy from the batteries. in which order does the energy change form? a. from chemical to electric to light energy b. from electric to light to chemical energy c. from electric to chemical to light energy d. from light to electric to chemical energy

Dna has unique properties that allow it to accurately retain genetic information, even after multiple rounds of replication. one aspect of dna that allows it to accurately store genetic information is the base pairing from chargaff\'s first rule of the four nucleotide bases. if the c content of a dna molecule is 22%, what are the percentages of the remaining bases?

Describe two recent or ongoing space missions.