Answer:
The crown is not pure gold.
Explanation:
First convert pounds to grams.
1 lb = 453.592 g
5 lb = 2267.96 g
When the chemist placed the crown in water and measured the difference in volume, he was doing water displacement. He was measuring the volume of the crown. According to his measurements, the crown is 170 mL.
1170 - 1000 = 170
Now that you have the crown's volume, you can use the density of gold to determine the weight. If the crown is made of pure gold, the calculations will prove that the crown is indeed 5 pounds. If the calculations show a value that is greater than 5 pounds, the crown is not pure gold.
170 mL × 19.3 g/mL = 3281 g
3281 g > 2267.96 g
The crown is not made from pure gold.
Answer:
Pure substance: sugar
A chemical change: occurs when methane is burned.
Explanation:
Pure substances have definite <em>constant compositions</em> (reflected in formulas) and have their own <em>chemical properties</em>. On the other hand, mixtures are made of two or more pure substances (<em>variable composition</em>) and their chemical properties depend on each combination. From the list, only sugar is a pure substance (C₁₂H₂₂O₁₁), whereas seawater, air, lemonade, and milk are mixtures.
Chemical changes (chemical reactions) occur when pure substances transform into others, and therefore there are new formulas. Conversely, in physical changes, pure substances <em>preserve their identity</em> (formula) but have changes in their <em>physical properties</em>. Methane being burned is a chemical change since new substances are formed:
CH₄ + O₂ ⇄ CO₂ + H₂O
Water vaporization, paper shredding and dissolution of solids in liquids are examples of physical changes.
Answer 1 hope I have helped you
