The identity of an element is determined by A. the number of neutrons
B. the weight of the nucleus
C. the number of protons
D. the number of electrons

The answer is Number of Protons !

i believe the answer is a.

8 m/s because for him to get the same amount of energy as ray is putting out, bobby, who weighs half as much as ray, needs to run twice as fast.

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.