Frogs and toads belong to this class of animal.
The green substance found in plant cells.
The line in the distance where the sky seems to meet the earth.
This colorless, sweet-smelling liquid was formerly used as a general anesthetic.
Pb is the symbol for this metallic element.
Hydrophobia is a morbid fear of what?
What unit is used to measure the loudness of a sound?
This large muscle between your lungs and your stomach helps you breathe.
An elementary particle with a negative charge that moves around the nucleus.