A sample of a radioactive isotope initially contains 20 x 10^10 atoms. After 16 days, 5 x 10^10 atoms remain. what is the half-life of the isotope?

A) 12 days

B) 20 days

C) 10 days

D) 16 days

E) 8 days

What is the heat of solution? A. the amount of heat released when a vapor changes into a liquid B. the amount of heat required to change a vapor into a liquid C. the amount of heat required to change a solid into a liquid D.

Write this numeral in scientific notation. 820.5

How many moles are in 2.35 grams of phosphorus?

14. A neutron has a charge of (1) + 1 (2) + 2 (3) O (4) - 1

An blank is a group of organisms that can mate and produce offspring that can mate

Chemical reactions are used to produce a variety of products, such as

How many grams are in 0.21mol sample of ethyl alcohol?

What is the scientific equesion to make antimatter?

How many molecules of molecular oxygen react with four molecules of NH3 to form four molecules of nitrogen monoxide and six molecules of water?

How many unchanged atoms would remain after 3 half-lives if the initial sample had 600 atoms? Explain.