The light rays in the illustration below do not properly focus at the focal point. This problem occurs with A. all-spherical mirrors
B. all parabolic mirrors
C. only defective spherical mirrors
D. only defective parabolic mirrors

Which sentences describe disadvantages of burning fossil fuels instead of using hydrogen fuel cells? burning fossil fuels contributes to climate change. burning fossil fuels takes place inside expensive fuel cells. fossil fuels aren't widely available, but pure hydrogen is. fossil fuels are nonrenewable.

If gases like carbon dioxide and methane make up less than 1% of the total atmosphere, why is it important for scientists to monitor changes in percentages of these gases?

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