8.1 Pure substances

What is the main ingredient in vaccines?

• Water

• Chlorine

• Carbonates

• Ibuprofen

What does a pure substance consist of?

• One substance only, nothing mixed with it

• Multiple substances mixed together

• Water and impurities

• Elements and compounds

Which of the following is an example of a pure substance?

• Tap water

• Seawater

• Silicon used in integrated circuits

• Ibuprofen powder used for vaccines

Why doesn't the vaccine company use tap water in its vaccines?

• Because it is readily available.

• Because it is impure and contains other substances.

• Because it is a compound.

• Because it is a painkiller.

What does purity describe?

• The amount of a substance in a mixture

• The color of a substance

• The temperature of a substance

• The taste of a substance

What is the purity of the water in the Arabian Sea?

• 100%

• 96.3%

• 3.7%

• Salty

What is the main ingredient in ibuprofen?

• H₂O

• NaCl

• C₁₃H₂₈0₂

• C₁₃H₁₈0₂

In 200 g of the powder contains 196 g of ibuprofen

What is the purity of the ibuprofen powder?

• 100%

• 98%

• Less than 98%

• Impure

What happens to the temperature of a pure substance while it melts or freezes?

• It increases steadily

• It decreases steadily

• It remains the same for a while

• It fluctuates

Which apparatus is used to investigate the purity/impurity of substances?

• Microscope

• Ammeter

• Thermometer

• Erlenmeyer flask