An ionic bond occurs between what particles?
a. 2 positive ions
b. two negative ions
c. two neutral ions
d. a positive and negative ion

Abird flies by moving its wings up and down. which two systems are most directly responsible for the movement of a bird's wings? a. skeletal and muscular systems b. respiratory and muscular systems c. skeletal and digestive systems d. respiratory and digestive systems

What is an example of a scientific question that galileo could not have answered with out this new tool?

Sharks depend on production for survival