The mass number of an element is equal to

a. the total number of electrons.

b. the sum of the protons and neutrons.

c. less than twice the atomic number.

d. a constant number for the lighter elements.

how many moles of magnesium hydroxide are in 15 mL of milk magnesia (density of magnesium hydroxide 2.34g/mL)

What are example of dense things.

Find the pH of the 0.169 M NaOH solution in problem 4 (assume that the NaOH dissociates completely into Na and OH-) and its associated absolute uncertainty by propagating the uncertainty in concentration found in part b of the problem.

Will upvote! Use the relationships between properties of gases to answer the following questions. a. When a balloon is placed in the freezer, it shrinks. Why? b. Aerosol cans often explode in fires. Why? c.

which one of these reactions is energy released? A all reactions B no reactions C endothermic reactions D exothermic reactions

4NH3 (g) + 502 (g) - >6H20g) + 4NOg) What is the enthalpy change for this reaction?

Carbon is black, crystalline and hard. Oxygen alone is a gas. How does the substance that is formed when these two elements combine differ from carbon?

When should you read the label on a chemical container?

How does acetaldehyde impurity arise in the fermentation?

What are the three parts that make up Earth's mantle?