Judge and improve a solution that reduces human impact

Grade 9 Science Worksheet

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.

   The plant emits 1,000 tons of SO2 without controls, and its limit is 60 tons. What removal percent does Ari need at least?

   • At least 60%, the permit number used as a percent
   • At least 94%, since 940 of 1,000 tons must be removed
   • At least 98%, the top of EPA's range for scrubbers
   • At least 6%, found as 60 ÷ 1,000 tons removed
3. 2.

   EPA's range for wet scrubbers is 90% to 98%. Bo checks the 60-ton limit. Which statement fits?

   • Meeting it needs 98%, since 95% still leaves 50 tons
   • Any scrubber in the range meets it, since 90% is a high figure
   • No scrubber in the range meets it, since 98% leaves 20 tons
   • Meeting it needs 94% or more; at 90% the plant emits 100 tons

4. 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.

5. 3.

   EPA gives 11.85 million tons of power-plant SO2 in 1995 and 0.65 in 2023. What percent drop does Esme find?

   • About 17%, found as 11.2 ÷ 0.65, the drop over the end
   • About 98%, the top of the scrubber removal range
   • About 5.5%, found as 0.65 ÷ 11.85, the amount left
   • About 95%, found as 11.2 ÷ 11.85

6. 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%)

7. 4.

   Jun asks how many more tons the U.S. would divert if recycling and composting rose from 32.1% to 50% of 292.4 million tons.

   • About 18 million tons more, found as 17.9 taken as tons
   • About 94 million tons more, the amount already diverted
   • About 52 million tons more, found as 17.9% of 292.4
   • About 146 million tons more, the whole 50% amount
8. 5.

   A city of 50,000 people makes 4.9 pounds of waste each per day. About how many tons does Luz get for a 365-day year?

   • About 89,400,000 tons, which leaves the pounds unconverted
   • About 4,470 tons, found by dividing by 20,000
   • About 122 tons, the amount made in just one day
   • About 44,700 tons, after dividing pounds by 2,000

9. Stormwater plans scored 1 to 5, 5 is best (model data)

   Plan	Runoff held back	Low cost	Low upkeep	Habitat
   J	5	3	1	1
   K	4	3	2	2
   L	3	2	4	4

   Note: Weights: runoff counts 3, cost counts 2, upkeep counts 1, habitat counts 1.

10. 6.

    Milo totals plans J, K and L with the weights on the card. Which plan scores highest?

    • Plan K, since it has no score as low as 1
    • Plan L, since it has the highest unweighted sum, 13
    • Plan J, with 23 weighted points
    • Plan L, since it leads on upkeep and habitat
11. 7.

    The town adds a constraint: every plan needs a cost score of at least 3. Which plans can Noah still pick, and which wins?

    • J and K stay; J wins with 23 points
    • The three plans stay; J wins with 23 points
    • J is out, since it has a score of 1; K wins with 22
    • J and K stay; K wins since it has fewer low scores
12. 8.

    Plan J's upkeep scores 1. Volunteer mowing would raise it to 3. What is J's new weighted total, by Ren's sum?

    • 27 points, up 4 because upkeep counts twice
    • 25 points, up 2 because upkeep counts once
    • 23 points, since upkeep is a limit, not a goal
    • 29 points, up 6 because 2 × 3 is the gain

13. 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.

14. 9.

    Tala sizes a rain garden to hold 372 gallons with 6 inches of ponding depth. Using 7.48 gallons per cubic foot, about how large?

    • About 200 square feet, found by using 3 inches of depth
    • About 50 square feet, which skips the depth of half a foot
    • About 25 square feet, found by using 2 feet of depth
    • About 100 square feet, since 372 ÷ 7.48 is 50 cubic feet

15. 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.

16. 10.

    A wet scrubber's weakest point is wastewater. Zee suggests one change that fixes it. Which change fits the EPA table?

    • Switch the scrubber off on rainy days, when it is least needed
    • Keep the wet scrubber but use less water, with no loss in removal
    • Use a dry scrubber, which needs no wastewater, and check its removal
    • Release the wastewater into a nearby river without treating it