Why are some isotopes radioactive?

Gold has a density of about 20g/mL. If I had a 60g sample, it should have a volume of about ___mL.

when you drop a block of metal into water, you find that the metal sinks. what happens if you drop a smaller block of the same metal into water?

Which of the following is true of an endothermic reaction? A. Strong bonds break and weak bonds form: this means that more energy is released than absorbed B.

The burning of methane gas, given below, is a redox reaction. which part of the reaction illustrates oxidation?

Natural selection can operate on predator populations as well as on prey. Suppose that over time trees became covered in lichen and the proportion of light moths increased to nearly 100%.

What happens when the cold finger is placed in the hot water? what direction did the heat travel from the hot water?

For a neutral Nitrogen, how many electrons are in the 2p electron orbitals?

A neutral atom has an atomic number of 20 and a mass number of 41; how many protons, neutrons, and electrons are found within the atom?

Which of the following are dwarf planets Ceres Nama is Eris Charon Haumea Makemake Pluto

Which set of factors changes igneous or sedimentary rock into metamorphic rock? heat and weathering water and weathering heat and pressure water and pressure