An isotope of an element will be radioactive if it has an unstable ratio

J. j. thomson’s experiment disproved the theory that an atom

How to tell if a molecule is polar or nonpolar with electronegativity

Why is rain likely when warm, moisture-laden air meets cold air? a) the lighter warm air will rise and cool down, causing condensation and rain. b) the cold air moves faster and pushes the warm air away, causing condensation and rain. c) the moisture in the warm air condenses on contact with the cold air, causing rain to fall. d) the cold air mixes with the warm air, reducing its temperature causing moisture to condense.