5.2 Purity

Elijah is studying chemistry and learns that a pure substance is important for his experiments. What does it mean for an element to be pure?

• It contains only one type of atom.

• It contains multiple types of atoms.

• It is mixed with other elements.

• It has a shiny appearance.

Noah is looking to buy a gold necklace and wants to know what 24 carat gold means.

• 100% pure gold

• 75% pure gold

• 50% pure gold

• 92.5% pure gold

Arjun is curious about how many parts out of 24 are gold in 18 carat gold.

• 18

• 24

• 6

• 12

Evelyn is considering buying a piece of jewelry made of 18 carat gold. She wants to know what the purity of 18 carat gold is before making her purchase.

• 50%

• 75%

• 92.5%

• 68%

Abigail is learning about metals in her chemistry class. What metals are commonly mixed with gold in alloys?

• Silver or copper

• Platinum or zinc

• Nickel or iron

• Boron or hydrogen

Ava is shopping for a silver necklace and wants to ensure she is buying high-quality silver. How is the purity of silver marked?

• By carats

• By parts per thousand

• By color

• By weight

While shopping for a gift, Benjamin comes across a beautiful silver necklace marked with 925. What does this mark indicate about the silver used in the necklace?

• 92.5% pure silver

• 90.0% pure silver

• 75% pure silver

• 50% pure silver

Charlotte is examining a piece of jewelry made of silver marked 925. How many atoms of other metals are in this silver?

• 925

• 75

• 900

• 100

Maya is shopping for silver jewelry and comes across two rings. One ring is marked with a purity of 900, while the other is marked with a purity of 925. Which mark indicates higher purity?

• 900

• 925

Aiden is trying to determine the purity percentage of silver in a piece of jewelry. How does he calculate it?

• parts of silver 1000 × 100

• parts of silver 24 × 100

• parts of silver 500 × 100

• parts of silver 100 × 100