Precious Metals

 

Precious Metals: 10 Interactive MCQs

Choose one answer for each question, then select Submit Quiz. Incorrect answers include an explanation based on the book.

1. What can affect the color of gold?

The shape of the gold grains Whether it was found in river gravel The amount and type of impurities it contains Its carat value alone

2. Why may gold be alloyed with other metals for jewelry?

To change its color and increase its hardness To make it tarnish more quickly To reduce it to a pure form To make it occur as river grains

3. What does the carat value of gold express?

The weight of one gold grain The gold’s crystal structure The amount of silver in the alloy The proportion of pure gold present

4. Where may gold be found in secondary placer deposits?

Only as large crystals in quartz As nuggets or grains in river sands and gravels Only as a by-product of lead mining As a black oxide on the surface of rocks

5. What causes the black tarnish that can form on silver?

Silver oxide forming when silver is exposed to oxygen in the air Pure silver changing into gold Silver grains absorbing river water A natural coating of copper in every silver specimen

6. What silver content does the book give for sterling silver?

20–25 percent 50 percent or more 92.5 percent or more Exactly 100 percent

7. What is electrum?

A gold alloy containing copper for rose color A silver alloy containing at least 95 percent silver A natural mixture of platinum and silver A gold-and-silver alloy containing 20–25 percent silver

8. When was platinum recognized as a chemical element, according to the book?

1493 1735 1920 Around 1900

9. What is one reason platinum does not tarnish like silver?

It is chemically inert and resistant to corrosion It is always covered with a layer of gold It is too soft to react with air It occurs only in river gravels

10. Why did platinum jewelry become more common after the 1920s?

Platinum was first found in river deposits then Platinum became softer than silver Technology had developed enough to work this high-melting-point metal Platinum was recognized as an element for the first time then