A recipe calls for 3.0 Tablespoons of salt to make a loaf of bread. You want to make 3 loaves of bread. If a Tablespoon is 3.3 cm3, how many cm3 of salt will you need?

A. 9.9 cm3

B. 9.0 cm3

C. 30 cm3

D. 29.7 cm3

solution

3 loaves 1

3.0 Tablespoons 1 loaf

3.3 cm3 Tablespoon

= 29.7 cm3

2 significant figures 30 cm3

A trip from LAX to Hawaii is 2650 miles. How far is that in km?

1 mile = 1600 meters

A. 4240 kmB. 1.63 kmC. 4.24 X 106 kmD. 4,000 km

solution

2650 miles 1

1600 m 1 mile

1 km 1000 m

= 4,240 km

A cube is 220.0 mm X 220.0 mm X 410 mm. What is its volume in cm3?

A. 198 cm3

B. 19844 cm3

C. 2.0 X 104 cm3

D. 440 cm3

solution

220 mm 1

1 m 1000 mm

100 cm 1 m

= 22 cm

Similarly:410 mm = 41 cm

Volume = length x width x height

V = 22 cm(22 cm)(41 cm) = 19844 cm3

2 significant figures = 2.0 X 104 cm3

There are 1.008 grams of hydrogen in one mole. One mole of a gas has a volume of 22.4 L. If you have 33 L of hydrogen, how many gramsdoes it weigh?

A. 1.5 gramsB. 745 gramsC. 1.49 gramsD. 63 grams

solution

33 Litres 1

1 mole 22.4 Litres

1.008 grams 1 mole

= 1.485 grams

2 significant figures, 1.5 grams

You’ve probably all seen the demonstration wherea card is put over the mouth of a glass of water andwhen the glass is flipped over and the card is released, the water doesn’t fall out. This is causedby the air pressure pushing up being stronger thanthe weight of the water pushing down. The cup that was used for this demo holds 110 mL of water.One mL of water weighs one gram.Air pressure is 13.5 pounds per square inch (lbs/sq. in.). How many square inches must the cup be for this trick to work? (1 pound = 453 grams)

A. 18 in2

B. .20 in2

C. .018 in2

D. 12 in2solution

110 ml 1

1 gram 1 mL

1 pound 453 grams

1 sq. inch 13.5 pounds

= .01799. . . sq. in.

2 significant figures, .018 sq. in.

1 2 3 4 5532

1 2 3 4 5