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Grade 7: Science subject test

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Subject practice test

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1. Analysis identifies new chemical products after a model process. What conclusion is stronger than bubbles alone? Which inference or prediction is best supported?Product identity supports a chemical reaction under the supplied record.Any bubbles always prove the same reaction.No atom totals need be conserved.Product analysis establishes every reaction rate.

2. Supplied case 6: initial total mass (g)=100; measured portion (g)=76, using the explicitly named quantities. Unmeasured retained mass equals initial system mass minus measured portion. What result follows?176 g25 g23 g24 g

3. Products have different connections but match every reactant element count. What follows? Which inference or prediction is best supported?Equal totals mean chemical identity cannot change.The counts prove the products’ temperature.New substances can form while atoms are conserved.Different bonds imply lost atoms.

4. A reaction model needs 15 J transferred into it before proceeding as specified. What is warranted? Which inference or prediction is best supported?The input alone identifies all products.The system receives energy; energy is transferred rather than destroyed.Input energy becomes nonexistent.Every receiving reaction releases the same amount immediately.

5. Two modeled gametes with one chromosome set each fuse. What follows? Which inference or prediction is best supported?One gamete’s chromosomes automatically disappear.Fusion is ordinary division into two cells.The fusion guarantees identical offspring traits.Their chromosome contributions combine in the modeled zygote.

6. A model leaf shape changes when light conditions change while the DNA sequence stays fixed. What is warranted? Which inference or prediction is best supported?Environment can never affect traits.One trait proves the identity of every gene.A trait can change without a demonstrated sequence mutation.Every visible change proves a new chromosome.

7. Supplied case 6: first gamete chromosomes=16; second gamete chromosomes=16, using the explicitly named quantities. Zygote chromosome count equals the two supplied gamete counts added. What result follows?31 chromosomes32 chromosomes256 chromosomes33 chromosomes

8. Two genotypes respond differently to the same light change. What inference fits? Which inference or prediction is best supported?The model supports genotype-by-environment differences.Light alone explains every result equally.Both genotypes must have identical responses.The pattern proves a clinical diagnosis.

9. Carbon dioxide moves from tissue blood to lung air in the model. Why is circulation relevant? Which inference or prediction is best supported?Gas exchange creates all carbon atoms.The route proves every tissue received nutrients.Blood transports the gas from tissues to the exchange site.Lungs directly touch every body cell.

10. After correction, the measured variable approaches its set range and the controller reduces output. What follows? Which inference or prediction is best supported?Reduced output proves the sensor failed.Feedback modifies the next signal as the measured state changes.The controller must ignore all new measurements.Output must stay maximal forever.

11. Supplied case 6: measured model units=14; reference model units=11, using the explicitly named quantities. Signed deviation equals measured value minus reference value. What result follows?3 model units25 model units4 model units2 model units

12. The sensor reports a change, but the controller sends no output. What follows? Which inference or prediction is best supported?No measurement exists despite the report.The effector must have completed correction.The model proves all real controllers fail.The record locates a missing control-output link, not necessarily a failed sensor.

13. A weather record says snowflakes survive to the ground rather than melt on descent. What condition is relevant? Which inference or prediction is best supported?One snowfall determines the long-term climate.The supplied descent-temperature conditions can preserve ice to the surface.Snow requires no water substance.Ground arrival proves every layer was above freezing.

14. A supplied ice sample melts into liquid with the same water identity. What follows? Which inference or prediction is best supported?Phase changes while chemical identity is retained.Water becomes an unrelated compound by definition.Matter necessarily disappears.Melting is the same direction as freezing.

15. Supplied case 6: first record (°C)=9; second record (°C)=12; third record (°C)=15, using the explicitly named quantities. Mean of three supplied values equals their sum divided by three. What result follows?36 °C13 °C11 °C12 °C

16. Matched records show heat-event frequency rising across decades. What kind of inference fits? Which inference or prediction is best supported?It proves every place has identical change.Any frequency comparison is invalid without one specific hot day.A long-term frequency change is climate-pattern evidence, with method/scope limits.It is only a forecast for tomorrow.

17. A spill is modeled upstream with a connected flow path to a later site. What is warranted? Which inference or prediction is best supported?The later site is a possible transport destination, not a guaranteed concentration.All material is destroyed at the upstream boundary.Distance alone proves complete removal.The map gives an exact exposure without flow or concentration data.

18. Pumping removes groundwater faster than model recharge replaces it. What follows? Which inference or prediction is best supported?Pumping creates unlimited recharge.Storage must rise because a pump runs.The balance proves every aquifer behaves identically.Stored groundwater declines under that stated balance.

19. Supplied case 6: initial water (L)=180; input water (L)=20; output water (L)=50, using the explicitly named quantities. Final store equals initial liters plus input liters minus output liters. What result follows?151 L149 L150 L250 L

20. A basin receives 30 L but has 20 L available retention capacity and no other exit. What follows? Which inference or prediction is best supported?Capacity has no relation to overflow.At least 10 L cannot be retained in the stated capacity model.All 30 L fit because retention creates capacity.The remaining 10 L must be purified.

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