Given the equation representing a reaction:

2Ca (s) + O2 (g) → 2CaO (s)

During this reaction, each element changes in

1) atomic number

2) oxidation number

3) number of protons per atom 4) number of neutrons per atom

In this reaction, the covalent bonds in the molecules of hydrogen and oxygen are broken. Is the bond breaking process exothermic or endothermic? Explain your answer.

What mass of anhydrous calcium chloride, CaCl2, should be dissolved in 590.0 grams of water in order to produce a 0.82 m solution

When moving upward on an energy pyramid from one level to the next, what happens to the usable energy in an ecosystem? It increases by about 10% It increases by about 90% It decreases by about 10% It decreases by about 90%

A researcher is performing a gram stain on a specimen in a medical laboratory. She gets distracted by a phone call and accidentally uses water instead of alcohol to decolorize. What may happen as a result of this mistake?

What forces must be overcome for a substance to melt

How should a stopper be handled after is has been removed from a reagent bottle?

Which of the following would most likely contain carbon? a. trees b. uranium c. water d. salt

Water becomes a gas. what step is this?

If 125 mL of a 1.1 M glucose solution is diluted to 500.0 mL, what is the molarity of the diluted solution? Express your answer using two significant figures.

What do you chemically call water?