State the rules governing the number of significant figures that result from each of the following operations addition and subtraction; mutiplication and divison

Which of the following reagents is an environmental toxin? Select all answers that apply. a. hydrazine sodium b. hydrosulfite triethylene c. glycol triethylene d. glycol 3-nitrophthalic acid e. hydrogen peroxide

What is the major difference between the two-dimensional and three - dimensional models of ethane and methane? When might you choose to use a two-dimensional model rather than a three-dimensional model when representing one of the molecules?

Why don't we use meters or miles when discussion distances between stars or galaxies?

The reaction between iodine and carbon dioxide to yield diiodine pentoxide is exothermic. How could the yield of diiodine pentoxide be decreased?

Potassium-40 (40k) is a radioactive isotope of potassium (atomic number 19). how many neutrons are located in the nucleus of potassium-40?

A gas at STP has a volume of 1.0 liter. If the pressure is doubled and the temperature remains constant, the new volume of the gas will be ... ?

Combustion analysis of toluene, a common organic solvent, gives 8.20 mg of co2 and 1.92 mg of h2o. if the compound contains only carbon and hydrogen, what is its empirical formula?

Why does the moon have phases? What are the four main phases of the moon? How long does it take to change from one to another?

How many atoms are in 1/2 mole of calcium

Which of the following units is best when measuring the mass of an object?