QUESTION: 161

An iceberg is slightly less dense than seawater and, therefore, floats with a fraction of its mass (about one-eighth to one-fifth) above the water. The other much greater portion is underwater. Irregularities in the shape of the iceberg determine how much is actually submerged.
Icebergs vary greatly in size and can present a great hazard to ships. Large icebergs are usually easy to detect on a ship's radar and, therefore, can be avoided.
Which statement is most important for a captain to recall when navigating a ship through an iceberg field?

Icebergs melt slowly.
Major portion of each iceberg is under water.
Smaller icebergs are not a threat to big ships.
Icebergs occur in clusters of ten or more.
Dangerous currents and eddies can surround an iceberg.

Answer(s): B

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QUESTION: 162

A loud sound, such as from a radio at a high volume, can be "deadened" more by hanging a heavy drape between the radio and the listener than by using a sheet of plywood.

Based on the information, which statement would justify this conclusion?

Sound waves would not reach the drape.
The drape absorbs more sound than the plywood does.
Plywood is harder to hang than drape.
The plywood absorbs more sound than the drape does.
The radio is playing louder than it should.

Answer(s): B

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QUESTION: 163

A physical change is a change that occurs in a substance without the formation of a different substance. In a chemical change, new substances are formed.
Which situation is an example of a chemical change?