A radioactive substance has a half life of one day. If you start with 100 grams of this substance, how much will be left after 2 days? *
100 g
50 g
25 g
12.5 g

Endeleev saw trends in the physical and chemical properties of elements when he organized them by

The speed of light is around 6.706×10^8 miles per hour. what is the speed of light in units of miles per minute?

Select each correct answer. more than one answer may be correct. which of the following is a characteristic of unicellular organisms? they can possess tissues and organs. all of their functions are performed by a single cell. they are usually microscopic. each of their cells is specialized to perform a specific function.