Grade 9 · Science · Unit 6 of 10
Chemistry & the Environment
pH, pollutants and water quality
What your child practises
The pH scale, acid rain and neutralization, nutrients and fertilizer runoff, indicator species, how substances such as mercury build up in food chains, and why the amount of a substance matters for safety.
Alberta Curriculum learning outcome: Unit C: Environmental Chemistry · acids and bases, nutrients and pollutants, air and water quality, and how substances build up in living things
Sample questions
A taste of this unit. In the app, questions change every time and get easier or harder to match your child.
Question 1
DDT and mercury are hard for living things to break down. What happens to them in a food chain?
- They disappear at each step
- They build up in the bodies of animals higher in the chain
- They are all passed to the producers
- They are found only in plants
Show answer
They build up in the bodies of animals higher in the chain
Hint: This build-up is called biomagnification, and top predators may have the highest amounts.
Question 2
Fertilizer from fields runs off into a lake and the water turns green with algae. This is caused mainly by too much…
- oxygen
- phosphorus and nitrogen
- ice
- helium
Show answer
phosphorus and nitrogen
Hint: These nutrients let algae grow fast. When the algae die and decay, they use up the oxygen that fish need.
Question 3
A solution has a pH of 10. What is it?
- neutral
- a base
- an acid
- a gas
Show answer
a base
Hint: A pH above 7 is basic (alkaline).
Question 4
A 4 L water sample contains 36 mg of nitrate. What is the concentration, in mg per litre?
answer boxmg/L
Show answer
9 mg/L
Hint: Concentration is amount divided by volume: 36 ÷ 4 = 9 mg/L.
Question 5
Which is more acidic, a solution with pH 4 or a solution with pH 5?
- They are equally acidic
- pH 5
- pH 4
Show answer
pH 4
Hint: The lower the pH, the more acidic the solution. A pH of 4 is 10 times more acidic than a pH of 5.
Question 6
Which of these is essential for strong bones and teeth?
- chlorine gas
- calcium
- mercury
- lead
Show answer
calcium
Hint: Calcium is a mineral the body needs for bones and teeth.