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# Physics

1. Which of the following is a correctly balanced equation?

a. P4 + 6 H2 --- 4 PH3
b. 1 P4 + 6 H2 --- 4 PH3
c. 0 P4 + 6 H2 --- 4 PH3
d. 2 P4 + 12 H2 --- 8 PH3
e. P4 + 3 H2 --- PH3

2. If the relative mass of a pingpong ball is 1/20 that of a golf ball, how many pingpong balls would you need to equal the mass of two golf balls?

a. 6.022 × 10^23
b. 100
c. 20
d. 24
e. 40

3.How is Avogadro's number related to the numbers on the periodic table?

a. The masses are all divisible by Avogadro's number, which gives you the weight of one mole.
b. The periodic table tells you the mass of one atom. From that, and Avogadro's number you know the number of moles.
c. The mass listed is Avogadro's number.
d. The atomic mass listed is the mass of Avogadro's number's worth of atoms.
e. The periodic table only gives us atomic numbers, not atomic mass.

4.What is the mass of an oxygen atom, O, in atomic mass units?

a. 18 amu
b. 12 amu
c. 32 amu
d. 16 amu

5. When we breathe we inhale oxygen, CO2, and exhale carbon dioxide, CO2, plus water vapor, H2O. Which likely has more mass, the air that we inhale or the same volume of air we exhale? Does breathing cause you to lose or gain weight?

a. The air we exhale has more mass; Breathing causes you to lose weight.
b. The air we exhale has more mass; Breathing causes you to gain weight.
c. The air we inhale has more mass; Breathing causes you to gain weight.
d. The air we inhale has more mass; Breathing causes you to lose weight.

6. For the above energy profiles, which reaction has the highest activation energy?

a. a
b. b
c. c
d. d
e. All have the same activation energy.

7.What is a reaction rate?

a. It is the ratio of the masses of products and reactants.
b. It is the balanced chemical formula that relates the number of product molecules to reactant molecules.
c. It is the speed at which reactants are consumed or product is formed.
d. It is the ratio of the molecular masses of the elements in a given compound.
e. none of the above

8. How does a catalyst increase the rate of a reaction?

a. It lowers the activation energy.
b. It increases the energy difference between the reactants and products.
c. It raises the activation energy of the reactants, which makes the reaction proceed faster.
d. It is neither created nor consumed in a reaction.
e. It has nothing to do with the rate of reaction.

9. Is the synthesis of ozone, O3, from oxygen, O2, an example of an exothermic or endothermic reaction?

a. exothermic because ultraviolet light is emitted during its formation
b. endothermic because ultraviolet light is emitted during its formation
c. endothermic because ultraviolet light is absorbed during its formation
d. exothermic because ultraviolet light is absorbed during its formation

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