Which two elements have the same number of valence electrons?

A.) Na and Sr

B.) Zr and H

C.) O and S

D.) Mg and P

If an atom has three protons three neutrons and two electrons what is the electrical charge of the atom

The saber toothed cat fossil is found i layer g this finding indicates that layers h and i must have formed during what time

4.80 x 10^25 formula units pf calcium iodide (Cal2) will have what mass?

Given the following equation: 2F2 + 2H2O = 4HF + O2 What mass of fluorine is needed to completely react with 3.6 grams of water? Molar mass of F2 = 38.00 g/mol Molar mass of H2O = 18.02 g/mol

Consider the statement: "The temperature of the land is an important factor for the ripening of oranges, because it affects the evaporation of water and the humidity of the surrounding air.

2 human activities that contribute to runoff into water systems

Which of the following is an example of geographic isolation? A. a population of salmon dies out because they cannot find food. B. a zebra with a long mane moves into a population of zebras with short manes. C.

What are moles in chemistry?

How did John dalton describe atoms?

Which of the following statements describes a physical property? The substance has a higher density than water. A. The substance forms a solid when reacted with silver nitrate. B. The substance is highly reactive. C.