Judge and improve a solution that reduces human impact

Grade 9 Science Worksheet - Building Confidence

Circle the best answer.

1. Read this first

   Card (model data)

   Without controls a plant emits 1,000 tons of SO2 a year, and its permit limit is 60 tons a year. EPA: wet scrubbers remove 90% to 98% of SO2.

2. 1.

   Ari reads that a plant would emit 1,000 tons of SO2 a year with no controls. A wet scrubber removes 90%. How much SO2 is still emitted?

   • About 10 tons a year, found as 1,000 × 1%
   • About 100 tons a year
   • No SO2, since a scrubber removes it entirely
   • About 900 tons a year, the amount removed

3. Table, Power-plant SO2 and scrubbers (EPA), with columns Measure, EPA figure

   SO2 from power plants, 2023, 0.65 million tons; Drop from 1995 to 2023, 11.2 million tons (95%); Wet scrubbers remove, 90% to 98% of SO2; Wet scrubber trade-off, more water use and wastewater to treat; Dry scrubber trade-off, no wastewater; What cut SO2 since 1995, controls, lower-emitting fuels and other changes.

4. 2.

   EPA: 2023 power-plant SO2 was 0.65 million tons, 11.2 million tons below 1995. What were 1995 emissions, by Esme's sum?

   • About 10.55 million tons, found as 11.2 − 0.65
   • About 0.65 million tons, the 2023 amount
   • About 11.85 million tons, found as 0.65 + 11.2
   • About 11.2 million tons, the size of the drop

5. Card (EPA)

   1 inch of rain on 1 square foot is 144 cubic inches, about 0.62 gallon. One cubic foot holds 7.48 gallons. A rain garden is a low planted area where runoff soaks in.

6. 3.

   One inch of rain falls on Kira's 600 square foot roof. Using EPA's 0.62 gallon per square foot, how much water is that?

   • About 144 gallons, the cubic inches per square foot
   • About 37 gallons, found as 600 × 0.062
   • About 3,720 gallons, found as 600 × 6.2
   • About 372 gallons, found as 600 × 0.62
7. 4.

   Goal 1: hold back runoff. Limit: spending of $50,000 or less. A town wants less runoff but cannot spend more than $50,000. Luz labels the two ideas. Which labeling is correct?

   • Both are criteria, since a design can be ranked on money
   • The $50,000 cap is a criterion; holding back runoff is a constraint
   • Both are constraints, since a design cannot score them
   • Holding back runoff is a criterion; the $50,000 cap is a constraint

8. Use the table

   U.S. waste, 2018 (EPA)

   Pathway	Million tons
   Total generated	292.4 (4.9 pounds per person per day)
   Recycled	69.0
   Composted	24.9
   Other food management	17.7
   Burned with energy recovery	34.6 (11.8%)
   Landfilled	146.1 (50%)
   Recycled and composted	almost 94 (32.1%)

9. 5.

   EPA: 69.0 million tons were recycled and 24.9 composted in 2018. What does Milo get for both together, and what share of 292.4?

   • About 112 million tons, about 38% of the waste
   • About 69 million tons, about 24% of the waste
   • About 146 million tons, about 50% of the waste
   • About 94 million tons, about 32% of the waste
10. 6.

    EPA: each person generated 4.9 pounds of waste a day in 2018. About how much is that over Noah's 365-day year?

    • About 17,900 pounds, close to 9 tons
    • About 1,790 tons, since a year is long
    • About 179 pounds, close to 0.09 ton
    • About 1,790 pounds, close to 0.9 ton
11. 7.

    Pia asks which pathway took the largest share of U.S. waste in 2018, and about how much. What does the EPA table show?

    • Burning with energy recovery, at about a quarter
    • Other food management, at about a fifth
    • Landfilling, at about half of the waste
    • Recycling and composting, at about a third

12. Card (EPA)

    a landfill has a flexible membrane over two feet of compacted clay, leachate collection, frequent soil cover, groundwater monitoring, and care after it closes.

13. 8.

    Ren reads about modern landfills. According to EPA, which parts protect groundwater?

    • A concrete lid that is sealed after the first day
    • A flexible membrane over compacted clay, with leachate collection
    • A layer of loose sand with open drains at the edge of the cell
    • A pond beside the cell that stores leachate in the open
14. 9.

    Leachate is liquid that drains through waste. A landfill collects it so it cannot reach groundwater. Tala sees the word leachate on an EPA landfill card. What is it, and what happens to it?

    • Clay under the cell; it is dug up for reuse after a year
    • Liquid that drains through waste; it is collected, not left to seep out
    • Gas that rises from the waste; it is vented straight to the air
    • Soil placed over the waste; it is spread out each week
15. 10.

    Landfill rules include groundwater monitoring, and closure and post-closure care. Zee's friend says a full landfill needs no more care once soil covers it. Which reply fits EPA?

    • No: the whole landfill must be dug up and burned
    • Yes: once soil covers the waste, nothing more is needed
    • Yes: the liner works without any monitoring after closing
    • No: closure and post-closure care continue, with monitoring