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Free Scientific Reasoning MCQs with Answers

334 Scientific Reasoning MCQs from Analytical and Logical Reasoning, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.

Scientific reasoning evaluates hypotheses through observations, variables, controls, measurements and experimental results. Questions involve identifying independent and dependent variables, recognising a fair test, interpreting tables or graphs, distinguishing evidence from opinion, and deciding whether data supports, rejects or leaves a hypothesis unresolved.

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334 questions · page 1 of 17

1. Twenty flies are placed in each of four glass tubes. The tubes are sealed. Tubes I and II are partially covered with black paper; Tubes III and IV are not covered. The tubes are placed as shown. Then they are exposed to blue light for five minutes. The number of flies in the uncovered part of each tube is shown in the drawing.These data show that these flies respond to (respond means move to or away from):

  • A. Blue light but not gravity
  • B. Gravity but not the blue light
  • C. Both blue light and gravity
  • D. Neither blue light nor gravity

Explanation: Comparing tubes III and IV, we can see that when there was a height difference in tube III, there were more flies in the upper half (19)…

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Correct answer: Blue light but not gravity

2. Farmer Brown was observing the mice that live in his field. He discovered that all of them were either fat or thin. Also, all of them had either black tails or white tails. This made him wonder if there might be a link between the size of the mice and the color of their tails. So he captured all of the mice in one part of his field and observed them. Below are the mice that he captured Is there a link between the size of the mice and the color of their tails?

  • A. There appears to be a link between size and tail color
  • B. There appears not to be a link between size and tail color
  • C. It is impossible to make a reasonable guess about a link
  • D. The size of the mice causes the tail color to change

Explanation: With very few exceptions, fat mice usually have black tails and small mice had white tails.

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Correct answer: There appears to be a link between size and tail color

3. A cleaning solution is used to remove limescale, CaCO3, from bathroom surfaces. When the solution is sprayed onto the limescale, effervescence (fizzing) occurs and the solid limescale begins to disappear. This chemical reaction is needed because the limescale cannot be removed with water alone. Which of the following statements about this chemical reaction are correct? 1 The cleaning solution is acidic. 2 The effervescence (fizzing) is caused by the release of hydrogen gas. 3 The pH of the reacting solution will go down as the reaction proceeds. 4 The salt produced in the reaction is more soluble than CaCO3

  • A. 1 and 3 only
  • B. 1 and 4 only
  • C. 2 and 3 only
  • D. 1, 3 and 4

Explanation: The correct answer is C, which means that only statements 1 and 4 are correct.Statement 1 is correct because limescale is composed of…

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Correct answer: 1 and 4 only

4. A news agent sells four different 'puzzle magazines. Information about these magazines is given in the following table. Hammad went into the newsagent yesterday to buy one of these magazines. He chose the one that offered him the least cost per puzzle.Which magazine did Hammad choose?

  • A. Puzzlemania
  • B. Thinking Today
  • C. Number Crunch
  • D. Mathematical Genius

Explanation: Cost Per Puzzle for Puzzlemania = 3.20/64 = $0.05 per puzzleCost Per Puzzle for Thinking Today = 2.40/30 = $0.08 per puzzleCost Per Puzzle…

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Correct answer: Puzzlemania

5. If 10 clothes are dried up together in 1 hour, in how many hours can 20 clothes be dried up together?

  • A. 1 hour
  • B. 2 hours
  • C. 3 hours
  • D. 4 hours

Explanation: If 10 clothes are dried up together in one hour, it means it took each piece of clothing 1 hour to dry up completely.

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Correct answer: 1 hour

6. I want to cut 10 identical rectangles each 6 cm x 10 cm, from rectangular plastic boards that are 15 cm x 20 cm. Each of the 10 rectangles must be cut out as one piece - joins are not allowed.What is the smallest number of plastic boards that I can use?

  • A. 2
  • B. 3
  • C. 4
  • D. 5

Explanation: To cut 10 identical rectangles, each measuring 6 cm x 10 cm, we need a total of 600 cm² of material.Each plastic board has an area of 15…

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Correct answer: 3

7. Max comes from Belize, one of the few countries to use the month/day/year form for writing dates rather than day/month/year. His date of birth was written 5/4/1996 but mistaken to be 5th April instead of 4th May. How many days in a year give a valid but different date when read the wrong way?

  • A. 66
  • B. 72
  • C. 132
  • D. 144

Explanation: Since Max's date of birth was mistaken to be 5th April instead of 4th May, we can assume that the day and month were swapped.

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Correct answer: 132

8. Mr and Mrs Porter drove down to see Sweeney. Mr Porter drove the first 20 km on the way there, and Mrs Porter drove the rest of the way. On the return journey, she drove the first 30 km and he drove the rest.How much farther did Mrs Porter drive than Mr Porter?

  • A. No farther
  • B. 10 km
  • C. 20 km
  • D. There is not enough information to work it out

Explanation: Distance to sweeney = xMr. Porter drove 20 km on the initial journey, and (x-30) km on the return journey.Total distance Mr.

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Correct answer: 20 km

9. This morning I took my three children to an internet cafe. Jay used the internet for 37 minutes and was charged $17.40, whilst Kay's 56 minutes cost $20.25, and Harry had to pay $19.05 for the 48 minutes that he spent online. Which of the following formulae does this cafe use to charge for its internet facilities?

  • A. $4.65 + $0.30 per minute
  • B. $8.15 + $0.25 per minute
  • C. $9.05 + $0.20 per minute
  • D. $11.85 + $0.15 per minute

Explanation: To determine which formula the cafe uses to charge for its internet facilities, we can analyze the given information.Let's consider Jay's…

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Correct answer: $11.85 + $0.15 per minute

10. An _ involves introducing a change to the treatment group, whereas in an _, the treatment group is based on current behavior.

  • A. Experiment; observational study
  • B. Observational study; experiment
  • C. Observational study; observational study
  • D. Experiment; experiment

Explanation: In an experiment, researchers introduce a change or intervention to the treatment group and observe the effects of that change.

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Correct answer: Experiment; observational study

11. A urologist is a doctor who specializes in disorders of the urinary system. Which of the following patients is most likely to be treated by a urologist?

  • A. A patient with low levels of iron in her blood
  • B. A patient with chronic indigestion
  • C. A patient with swollen veins in the anus, called hemorrhoids
  • D. A patient with a painful kidney stone

Explanation: The patient most likely to be treated by a urologist is B) a patient with a painful kidney stone.A urologist specializes in disorders of…

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Correct answer: A patient with a painful kidney stone

12. Genetically modified crops and livestock offer the possibility of greater yield and food quality, reductions in pesticide use, and higher profits for agricultural businesses. They are viewed by some as a way to help reduce world hunger by increasing food production and reducing losses to pests and varying environmental conditions. Each year, industrial agriculture relies more heavily on genetically modified crops. There are some concerns about our increasing use of genetically modified crops and livestock, including their safety for human consumption and their effects on the environment.Based on the passage above, if genetically modified crops were to be banned, what could be the largest negative impact to humans?

  • A. Introduction of new allergens into the food supply
  • B. Loss of genetic diversity in food crops
  • C. Decreases in food production worldwide
  • D. Increase in the amount of beneficial insects

Explanation: Based on the passage, if genetically modified crops were to be banned, the largest negative impact to humans would likely be option C)…

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Correct answer: Decreases in food production worldwide

13. Battery companies make impressive claims about how long their batteries will last. A student decided to test the running time of different batteries to determine which battery lasts the longest. The student tested 6 different batteries, 4 brand name and 2 generic, using flashlights. The results show that the battery referred to as Name Brand A lasted the longest, with 101 hours of runtime: It could be argued that this experiment was not set up using proper experimental protocol. What would need to change in the experiment for the results to be valid?

  • A. The batteries should have all been either name brand or generic
  • B. Only two groups should have been tested at a time
  • C. The same battery should have been used in each flashlight
  • D. The same flashlight should have been used to test each battery

Explanation: The same flashlight should have been used to test each battery: This is the correct answer.

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Correct answer: The same flashlight should have been used to test each battery

14. Which of the following statements about photosynthesis is correct?

  • A. When 6 molecules of carbon dioxide are used, 1 molecule of oxygen is produced
  • B. When 1 molecule of water is used, 1 molecule of glucose is produced
  • C. When 6 molecules of water are used, 1 molecule of glucose is produced
  • D. When 1 molecule of glucose is produced, 12 molecules of oxygen are used

Explanation: Photosynthesis is the process by which plants, algae, and some bacteria convert sunlight, water, and carbon dioxide into glucose (a sugar)…

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Correct answer: When 6 molecules of water are used, 1 molecule of glucose is produced

15. Wavelengths are measured in nanometers (nm). Each color on the visible spectrum has a different wavelength. The human eye is only able to distinguish wavelengths between 400-750 nm. The approximate wavelengths of the visible spectrum are shown below:If you were reading a scientific report, and it referred to a wavelength of 455 nm, which color would it be referring to?

  • A. Violet
  • B. Ultraviolet
  • C. Blue
  • D. Green

Explanation: Reading the spectrum provided in the question, it is evident that a wavelength of 455nm refers to the colour that lies in between 400nm…

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Correct answer: Blue

16. What is the median of number of hurricanes per decade?

  • A. 15.29
  • B. 15.5
  • C. 15
  • D. 17

Explanation: The median is the middle value in a set of data. First, organize and order the data from smallest to largest.

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Correct answer: 15

17. What is the range of this data set?

  • A. 15
  • B. 11
  • C. 20
  • D. 9

Explanation: The range of a data set is the difference between the maximum and the minimum values.1950s →20 hurricanes1960s →15 hurricanes1970s →12…

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Correct answer: 11

18. As part of a chemistry experiment, 1025 milliliters of water is mixed into a beaker that contains 175 milliliters of motor oil. After adding the water, how many liters of liquid are in the beaker?

  • A. 1.2L
  • B. 1200L
  • C. 1,200,000L
  • D. 12L

Explanation: To convert milliliters (mL) to liters (L), we need to divide by 1000.Total volume of liquid in the beaker = 1025 mL + 175 mL = 1200…

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Correct answer: 1.2L

19. When a cell reproduces through cell division, scientists call the reproducing cell the parent cell, and the two cells that result from the division are called daughter cells. The daughter cells are genetically identical to the parent cells. Before a parent cell starts to divide, the DNA in its nucleus replicates, or makes a complete copy of itself. Why is this process necessary?

  • A. So that the parent cell will have an extra copy of DNA
  • B. So that each daughter cell receives a complete set of DNA
  • C. So that each daughter cell will not need to synthesize proteins
  • D. So that each daughter cell will receive half its DNA from each parent cell

Explanation: The correct answer is B. The process of DNA replication before cell division ensures that each daughter cell receives a complete set of…

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Correct answer: So that each daughter cell receives a complete set of DNA

20. Which of the following is implied by the fact that seafloor spreading at the Mid-Atlantic Ridge is causing the Atlantic Ocean to widen by about 5 centimeters a year?

  • A. The Mid-Atlantic Ridge stretches over a vast distance across the ocean floor.
  • B. The Mid-Atlantic Ridge is the most prominent underwater feature in the Atlantic Ocean.
  • C. The continents of North America and Europe are moving apart.
  • D. The continents of North America and Europe are increasing in size due to the Mid-Atlantic Ridge.

Explanation: The correct answer is C. The fact that seafloor spreading at the Mid-Atlantic Ridge is causing the Atlantic Ocean to widen by about 5…

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Correct answer: The continents of North America and Europe are moving apart.
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Scientific Reasoning MCQs: common questions

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