maddyhelps

Science 9

Science 9 · Worksheets

Year-end challenge

Ten questions of mixed difficulty, covering Biological diversity, Electricity, Environmental chemistry, Matter and chemical change, Space exploration. Print it, or work through it on screen — the answer key starts on its own page.

All worksheets

Year-end challenge

Science 9 · maddyhelps.com

Name
Date
Score
/ 10

Circle the best answer for each question. Show your work in the space provided.

  1. A chemical has an LD50 of 100 mg/kg when tested on dogs. For a 20 kg dog, what dose matches the LD50?

    1. a) 80 mg
    2. b) 120 mg
    3. c) 2000 mg
    4. d) 5 mg

  2. Which statement about mutations is correct?

    1. a) A mutation is always harmful to the organism
    2. b) Every mutation is passed on to the offspring
    3. c) Mutations happen only after someone is exposed to radiation
    4. d) A mutation can be harmful, helpful or have no effect

  3. In a natural gas power plant, the order of energy changes from the fuel to the power line is

    1. a) chemical → thermal → mechanical → electrical
    2. b) thermal → chemical → mechanical → electrical
    3. c) chemical → electrical → mechanical → thermal
    4. d) chemical → mechanical → thermal → electrical

  4. Which of these concentrations is equal to 1 ppm (one part per million)?

    1. a) 1 g in 100 g
    2. b) 1 g in 1 kg
    3. c) 1 mg in 1 kg
    4. d) 1 mg in 1 g

  5. A star chart says a planet will be at altitude 30° and azimuth 90°. Where should you look?

    1. a) East, one third of the way up from the horizon
    2. b) North, one third of the way up from the horizon
    3. c) East, one third of the way down from overhead
    4. d) West, one third of the way up from the horizon

  6. Many cultures, including many First Nations, tracked the seasons by which stars could be seen after sunset. This works because

    1. a) the stars themselves change their positions every few months
    2. b) Earth's orbit brings different stars into the night sky over a year
    3. c) Earth's spin speeds up in summer and slows down in winter
    4. d) the stars move much closer to Earth during certain seasons of the year

  7. Which list goes from largest to smallest?

    1. a) gene, chromosome, nucleus
    2. b) chromosome, nucleus, gene
    3. c) nucleus, gene, chromosome
    4. d) nucleus, chromosome, gene

  8. Which of these is an organic compound?

    1. a) Glucose, C₆H₁₂O₆
    2. b) Water, H₂O
    3. c) Carbon dioxide, CO₂
    4. d) Table salt, NaCl

  9. A student heats a clear, colourless liquid in a dish until it all evaporates. A white solid is left behind. The liquid was

    1. a) a solution, which is a mixture
    2. b) a mechanical mixture of two liquids
    3. c) pure water, since it was colourless
    4. d) a pure substance, because it was clear

  10. A 120 V kitchen circuit is wired in parallel and protected by a 15 A breaker. A 900 W toaster and a 1200 W kettle are switched on together. What happens?

    1. a) Nothing: each appliance only gets 60 V
    2. b) Nothing: each appliance draws under 15 A
    3. c) The breaker trips: the currents add to 17.5 A
    4. d) The breaker trips: the two voltages add to 240 V

Answer key · Year-end challenge

Science 9 · maddyhelps.com

  1. c) 2000 mg — LD50 is given per kilogram of body mass, so multiply by the mass: 100 mg/kg × 20 kg = 2000 mg. Dividing 100 by 20 gives 5 mg, which would be the LD50 dose for an animal of only 0.05 kg.
  2. d) A mutation can be harmful, helpful or have no effect — A mutation is any change in DNA, and most have little or no effect; a few help and some harm. Only mutations in sex cells can be inherited, so one in a skin cell stays with that person.
  3. a) chemical → thermal → mechanical → electrical — Burning the gas releases its chemical energy as heat, the heat drives a spinning turbine, and the turbine turns a generator. Every step wastes some energy as heat, which is why the plant as a whole is less efficient than any one of its steps.
  4. c) 1 mg in 1 kg — A kilogram is a million milligrams, so 1 mg in 1 kg is one part in a million. For water, 1 kg is about 1 L, which is why 1 mg/L and 1 ppm are treated as the same; 1 g in 1 kg is a thousand times more concentrated.
  5. a) East, one third of the way up from the horizon — Azimuth is the compass direction measured clockwise from north, so 90° is east. Altitude is the angle up from the horizon, and 30° is a third of the way to the point straight overhead at 90°.
  6. b) Earth's orbit brings different stars into the night sky over a year — As Earth travels around the Sun, the night side faces a different part of space, so the visible stars change through the year in the same order every year. The stars have not moved; our viewpoint has, which is what makes them a reliable calendar.
  7. d) nucleus, chromosome, gene — The nucleus holds the chromosomes, each chromosome is one long strand of DNA, and a gene is a short section of that strand. A gene is part of a chromosome, never the other way round.
  8. a) Glucose, C₆H₁₂O₆ — Organic compounds contain carbon, usually bonded to hydrogen, and they are what living things are built from. Carbon dioxide contains carbon but is classed as inorganic, along with carbon monoxide and carbonates, which is the usual trap.
  9. a) a solution, which is a mixture — Something was dissolved in the liquid, so it held more than one substance: it was a solution. Clear does not mean pure, since salt water and sugar water are both perfectly clear.
  10. c) The breaker trips: the currents add to 17.5 A — Each branch gets the full 120 V, so I = P ÷ V gives 7.5 A for the toaster and 10 A for the kettle. In parallel the branch currents add, and 17.5 A is more than the breaker allows; each being under 15 A on its own does not matter.