ACT Science Practice Test: Chemistry and Physics Passages
- Chemistry and Physics Passages
- 10 questions
- 11 minutes
This test has two original passages, one on solubility and one on electric circuits, each followed by five questions. Several questions need a quick subtraction or division using values from the tables. Keep track of units such as grams per 100 g of water, ohms and amperes.
Tap an option to mark your answer. You can change your mind, or tap the same option again to leave the question blank. The correct answers and explanations appear when you finish the test.Tap an option to answer; tap it again to leave the question blank.
Your result
- 0 correct
- 0 wrong
- 0 blank
-
Question 1
Passage I
The solubility of a substance is the greatest mass that can dissolve in a given amount of water at a given temperature. A solution that holds this maximum mass is saturated; one that holds less is unsaturated. If a saturated solution is cooled and the solubility drops, the extra solid comes out of solution as crystals.
Table 1 gives the solubility of potassium nitrate (KNO3) and sodium chloride (NaCl) in grams of solid per 100 g of water.
Table 1 Temperature (°C) KNO3 (g/100 g water) NaCl (g/100 g water) 0 13.3 35.7 20 31.6 36.0 40 63.9 36.6 60 110.0 37.3 80 169.0 38.4 Between which two temperatures in Table 1 do KNO3 and NaCl have the same solubility?
Correct answer: B
At 20°C, KNO3 (31.6 g) is less soluble than NaCl (36.0 g); at 40°C it is more soluble (63.9 g versus 36.6 g). The two values must be equal somewhere between 20°C and 40°C.
-
Question 2
Passage I (see above):
Which statement best compares how temperature affects the two substances?
Correct answer: A
From 0°C to 80°C, KNO3 rises from 13.3 g to 169.0 g, while NaCl rises only from 35.7 g to 38.4 g. Both increase, so the choice saying both decrease is wrong.
-
Question 3
Passage I (see above):
A student dissolves 50.0 g of KNO3 in 100 g of water at 40°C. Which statement describes the solution?
Correct answer: D
At 40°C up to 63.9 g of KNO3 can dissolve in 100 g of water. With 50.0 g dissolved, the solution is unsaturated and could take 63.9 − 50.0 = 13.9 g more.
-
Question 4
Passage I (see above):
A saturated solution of KNO3 in 100 g of water at 60°C is cooled to 20°C. About how many grams of KNO3 will form crystals?
Correct answer: C
At 60°C the water holds 110.0 g; at 20°C it can hold only 31.6 g. The difference, 110.0 − 31.6 = 78.4 g, comes out as crystals. The choice 46.1 g uses the 40°C value instead of 20°C.
-
Question 5
Passage I (see above):
What is the smallest mass of water that can dissolve 73.2 g of NaCl at 40°C?
Correct answer: B
At 40°C, 100 g of water dissolves 36.6 g of NaCl. Since 73.2 g is twice 36.6 g, twice as much water, 200 g, is needed.
-
Question 6
Passage II
Students built circuits with a 12.0 V battery and resistors of known resistance, measured in ohms (Ω). An ammeter measured the current, in amperes (A), leaving the battery.
Experiment 1: A single resistor was connected to the battery.
Table 1 Resistance (Ω) Current (A) 10 1.20 20 0.60 30 0.40 40 0.30 60 0.20 Experiment 2: Two resistors were connected one after the other (in series), so the same current passed through both.
Table 2 Resistors Current (A) 10 Ω and 10 Ω 0.60 10 Ω and 20 Ω 0.40 20 Ω and 40 Ω 0.20 Experiment 3: Two resistors were connected side by side (in parallel), each directly across the battery. The total current leaving the battery was measured.
Table 3 Resistors Total current (A) 20 Ω and 20 Ω 1.20 20 Ω and 60 Ω 0.80 In Experiment 1, the product of the resistance and the current for each trial was closest to:
Correct answer: A
For every row, resistance × current = 12: for example, 10 × 1.20 = 12 and 40 × 0.30 = 12. This equals the battery voltage, 12.0 V, as Ohm's law predicts.
-
Question 7
Passage II (see above):
Based on Experiment 1, what current would most likely be measured with a single 24 Ω resistor?
Correct answer: B
Current = 12 ÷ 24 = 0.50 A, which also fits between the values for 20 Ω (0.60 A) and 30 Ω (0.40 A). The choice 2.0 A divides 24 by 12 instead, and 2.88 A multiplies the resistance by 0.12.
-
Question 8
Passage II (see above):
According to Tables 1 and 2, a 10 Ω resistor and a 20 Ω resistor in series give the same current as a single resistor of:
Correct answer: D
The series pair gives 0.40 A, the same current as the single 30 Ω resistor in Table 1. In series, resistances add: 10 + 20 = 30 Ω. The value 6.7 Ω is what the same pair would act like in parallel.
-
Question 9
Passage II (see above):
Compared with a single 20 Ω resistor in Experiment 1, adding a 60 Ω resistor in parallel (Experiment 3) made the total current leaving the battery:
Correct answer: C
The single 20 Ω resistor drew 0.60 A; with the 60 Ω resistor added in parallel, the total was 0.80 A. A parallel branch adds a new path for current, so the total rises even though the new resistor is large.
-
Question 10
Passage II (see above):
In the Experiment 3 circuit with the 20 Ω and 60 Ω resistors, how much current most likely passed through the 60 Ω resistor?
Correct answer: A
Each parallel resistor is directly across the 12.0 V battery, so the 60 Ω branch carries 12 ÷ 60 = 0.20 A. The 20 Ω branch carries 0.60 A, and together they make the measured 0.80 A total. The value 0.15 A would apply if the two resistors were in series (12 ÷ 80).
Questions you leave blank are not counted as wrong.
More Science tests
ScienceACT Science Practice Test: Calculations with Scientific DataCalculations with Scientific Data10 questions10 min ScienceACT Science Practice Test: Data RepresentationData Representation12 questions12 minScienceACT Science Practice Test: Research Summaries and Conflicting ViewpointsResearch Summaries and Conflicting Viewpoints12 questions12 minScienceACT Science Practice Test: Mixed PracticeData, Experiments and Viewpoints12 questions12 minScienceACT Science Practice Test: Experimental Design and VariablesExperimental Design and Variables10 questions11 minScienceACT Science Practice Test: Life Science and Earth Science PassagesLife Science and Earth Science Passages10 questions11 minScienceACT Science Practice Test: Interpolation and ExtrapolationInterpolation and Extrapolation10 questions10 min