1. A chemical reaction produces a gas that forms a

spherical balloon with a radius of 10 cm. What is the

volume of the gas inside the balloon? Use the formula V =

(4/3)πr^3 for the volume of a sphere.

a) 314 cm^3

b) 4188 cm^3

c) 1257 cm^3

d) 628 cm^3

Answer: B. The volume of the gas is equal to the volume of

the sphere, so we plug in r = 10 into the formula and get V

= (4/3)π(10)^3 = 4188 cm^3.

2. A chemist wants to measure the distance between two

atoms in a molecule using a microscope. The microscope

has a magnification of 1000x and the atoms appear to be 2

mm apart on the screen. What is the actual distance

between the atoms in nanometers? Use the fact that 1 mm =

10^6 nm.

a) 2 nm

b) 2000 nm

c) 0.002 nm

d) 0.2 nm

Answer: C. The actual distance between the atoms is equal

to the apparent distance divided by the magnification, so

we divide 2 mm by 1000 and get 0.002 mm. Then we

multiply by 10^6 to convert to nanometers and get 0.002

nm.

3. A chemical compound has a molecular formula of