Which of the following statements is false?
a. two or more different substances combine physically to form a mixture.
b. two or more different atoms combine chemically to form an element.
c. two or more elements combine chemically to form a compound.
d. two or more atoms combine chemically to form a molecule.

What are chlorofluorocarbons and what impact do they have on the atmosphere?

Which pair of quantities includes one quantity that increases as the other decreases during simple harmonic motion?

An electron moves with a constant horizontal velocity of 3.0 × 106 m/s and no initial vertical velocity as it enters a deflector inside a tv tube. the electron strikes the screen after traveling 26 cm horizontally and 19 cm vertically upward with no horizontal acceleration. what is the constant vertical acceleration provided by the deflector? (the effects of gravity can be ignored.)