Which definition describes a half-life?

the time required for half of a radioactive sample to decay.

the time required for half of a radioactive sample to become unstable.

the time required for all of a radioactive sample to change because of heat.

the time required for all of a sample to break down due to pressure change.

Which of the following compounds does not contain molecules? question 2 options: co2 h2 nacl h2o

Which type of bonding involves the complete transfer of a valence electron from a less electrogrative atom to a more electronegative one

Maria wants to determine which type of disinfectant kills the most bacteria. which of the following is the best way for maria to determine this? a. ask ten different companies that make disinfectants which type is best. b. put the same amount and species of bacteria on ten identical plates, and add ten different kinds of disinfectant to each plate. c. interview ten different people to determine which type of disinfectant they prefer. d. put the same amount and species of bacteria on ten identical plates, and add a different disinfectant to each plate.