9.3: pH and Indicators

Baking powder is dissolved in water.
Universal Indicator is added and the solution turns blue. A pH colour chart shows the solution to have a pH of 9.  
What is baking powder?

• a strong acid
• a strong alkali
• a weak acid
• a weak alkali

Universal Indicator turns purple when added to a colourless solution X. What could solution X be?

• hydrochloric acid
• sodium chloride solution
• aqueous ammonia
• sodium hydroxide solution

Solid sodium hydroxide can be added to pure water to make sodium hydroxide solution. Which pH change shown in the table can occur?

• A
• B
• C
• D

Compound X is used to control soil acidity. What is X?

• calcium chloride
• calcium hydroxide
• calcium nitrate
• calcium sulfate

Soil in a garden has a pH of 6.5. The pH of the soil is changed by adding calcium hydroxide. Which plant needs calcium hydroxide to be added to the soil for the plant to grow well?

• A
• B
• C
• D

A garden has soil with a pH of 6.5.
Cabbages grow best in soils with a pH of 7.5. The cabbages grow better when calcium hydroxide is added to the soil in the garden. Which row in the table is correct?

• A
• B
• C
• D

The chart shows the position of four substances on the pH scale. Which substance will turn Universal Indicator red?

• A
• B
• C
• D

The graph shows how the pH value of the soil in a field changed over time. At which point is the soil most acidic?

• A
• B
• C
• D

The chart shows the colour ranges of four different indicators. Which indicator is blue in an acidic solution?

• A
• B
• C
• D