Acid, alkalis and salts

Which of the following is true of an acid?

• It has a pH value of 7.

• It turns red litmus paper blue.

• It turns blue litmus paper red.

• It has a pH value of more than 7.

All acids have a pH higher than 7.

• True

• False

When a Universal Indicator is added to sulphuric acid, the solution turns red.

• True

• False

When a Universal Indicator is added to a solution of potassium hydroxide, the solution turns blue.

• True

• False

When acids and alkalis react, salts of neutral pH are formed.

• True

• False

Toothpaste can neutralise the acids produced by bacteria feeding on the food stuck on our teeth.

• True

• False

What will happen when Sodium Hydroxide solution is added gradually to a conical flask of dilute nitric acid containing Universal Indicator?

• The pH increases.

• The pH decreases.

• The colour of the indicator will not change.

• The colour of the indicator changes from blue to red.

Which of the following substances contain acid?

• An orange
• Bleach
• Distilled water
• Washing powder

Which of the following pH numbers indicates a neutral substance?

• 1
• 5
• 7
• 14

Which of the following pH numbers indicates a strong acid?

• 1
• 5
• 7
• 14