F2Y UNIT 9.2 Acid-alkali indicators and pH scale

Acids and alkalis cannot be distinguished by their appearances.

• T

• F

Litmus is a mixture of pigments extracted from lichen.

• T

• F

Universal indicator is a mixture of several indicators.

• T

• F

The pH value is expressed as a number from 1 to 14.

• T

• F

Answer explanation

The pH value is expressed as a number from 0 to 14.

The pH value should be an integer and cannot be expressed with decimal places.

• T

• F

Answer explanation

The pH value does not have to be an integer and can be expressed with decimal places.

Litmus paper can be used to indicate the degrees of acidity or alkalinity of a substance?

• T

• F

Which of the following indicators CANNOT be used to test for alkalis?

• Red litmus paper

• Blue litmus paper

• pH paper

• Universal indicator

Stronger acids have a pH closer to...

• 7

• 0

• 14

• 9

Weaker alkali have a pH closer to...

• 8

• 0

• 14

• 4

A pH level of 7 indicates

• acid

• alkali

• neutral

• none of the above