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 94%, since 940 of 1,000 tons must be removed
   • At least 60%, the permit number used as a percent
   • At least 6%, found as 60 ÷ 1,000 tons removed
   • At least 98%, the top of EPA's range for scrubbers
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
   • No scrubber in the range meets it, since 98% leaves 20 tons
   • Any scrubber in the range meets it, since 90% is a high figure
   • 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 98%, the top of the scrubber removal range
   • About 95%, found as 11.2 ÷ 11.85
   • About 5.5%, found as 0.65 ÷ 11.85, the amount left
   • About 17%, found as 11.2 ÷ 0.65, the drop over the end

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 52 million tons more, found as 17.9% of 292.4
   • About 94 million tons more, the amount already diverted
   • About 18 million tons more, found as 17.9 taken as tons
   • 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 122 tons, the amount made in just one day
   • About 44,700 tons, after dividing pounds by 2,000
   • About 89,400,000 tons, which leaves the pounds unconverted
   • About 4,470 tons, found by dividing by 20,000

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

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

    For a nature park, Pia makes habitat count 3 instead of 1. Which plan wins with the new weights?

    • Plan L, with 29 points
    • Plan J, with 25 points, since its runoff score is highest
    • Plan K, with 26 points, since it is in the middle
    • Plan J, with 23 points, since weights do not change a winner

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?

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