Free Scientific Reasoning MCQs with Answers

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) than in the lower half (1). Meanwhile when tube IV was examined, the left and right halves - which were at the same height - had an equal number of flies (10). This shows that the flies did indeed respond to gravity.When we compare tubes II and IV, both of these are horizontally placed but in tube II, one half is covered with black paper while the other half is exposed to blue light. As a result, there are 18 flies in the exposed region and 2 in the darkened region. When this is compared to tube IV which had an equal number of flies in either half, we can conclude that exposure to blue light is detected by and responded to by the flies.

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. However, this relationship is not enough to establish causality

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 calcium carbonate (CaCO3), which is a base, and an acid-based cleaning solution is needed to react with it. The acid in the cleaning solution can neutralize the base and break down the limescale.Statement 2 is incorrect because the effervescence is caused by the release of carbon dioxide gas, not hydrogen gas. When an acid reacts with a carbonate, carbon dioxide gas is produced as a byproduct, which is what causes the effervescence.Statement 3 is incorrect because the pH of the reacting solution will not actually decrease as the reaction proceeds.Statement 4 is correct because the salt produced in the reaction, calcium acetate (Ca(CH3COO)2), is more soluble than CaCO3. This means that it can dissolve in water more easily, allowing it to be rinsed away along with the limescale.Therefore, the correct answer is C, which includes only statements 1 and 4 as correct.

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 for Number Crunch = 1.80/30 = $0.06 per puzzleCost Per Puzzle for Mathematical Genius = 3.40/40 = $0.085 per puzzleThus, Hammad chose Puzzlemania, because it offered him the least cost per puzzle. The answer is Option A.

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. Therefore, 20 clothes, when dried up together, will also take 1 hour, as each piece of clothing takes one hour to dry, regardless of however many pieces of clothing are drying alongside it.

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 cm x 20 cm = 300 cm². Therefore, we need to calculate the total area of the material required to cut out 10 rectangles.To obtain a total area of 600 cm² (for 10 rectangles), we need at least 2 plastic boards. However, cutting out 6 rectangles from each of these two boards would require overlapping cuts, which is not allowed.From each 15 cm x 20 cm board, we can cut out only 4 rectangles without overlapping cuts. In order to get 10 rectangles, we need a minimum of three plastic boards to obtain 10 rectangles without any overlapping cuts.Therefore, the correct answer is B) 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. Therefore, the mistaken date would be 4/5/1996.For a valid but different date to be formed when read the wrong way, the month and day must be within the range of valid values for months and days.If we swap the day and month of a date, we get a valid but different date when both the day and month are within the range of valid values.For example, if the original date is 1/7/2023 (1st July 2023), swapping the day and month would give us 7/1/2023 (7th January 2023), which is a valid but different date.In each month, the first 12 days are the ones that will give a valid date when day and month can be switched to still obtain a valid date. However, in each month there are only 11 dates that can give valid but different date, because one of the first 12 dates will hold the same day and month, example 2nd February is 2/2 so swapping it won't make a difference.Taking the example of February to calculate:2/1, 2/3, 2/4, 2/5, 2/6, 2/7, 2/8, 2/9, 2/10, 2/11, 2/122/13--- 2/31 can't be misread.Same is the case of rest of the 11 months.So the number of dates that can be misread are: 11 × 12= 132Therefore, the answer is C) 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. Porter drove = 20 + x - 30 = (x-10) kmMrs. Porter drove (x-20) km on the initial journey, and 30 km on the return journey.Total distance Mrs. Porter drove = x - 20 + 30 = (x+10) kmDifference between total distance of Mrs. Porter and Mr. Porter=(x+10) - (x-10)= x + 10 - x + 10=20 kmTherefore, the answer is option C.

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 charges:Jay used the internet for 37 minutes and was charged $17.40.If we assume the formula for Jay's charges is A + (B x no. of minutes), we can set up an equation:$17.40 = A + 37BNow, let's consider Kay's charges:Kay used the internet for 56 minutes and was charged $20.25.If we assume the formula for Kay's charges is A + (B x no. of minutes), we can set up an equation:$20.25= A + 56BNext, let's consider Harry's charges:Harry used the internet for 48 minutes and was charged $19.05.If we assume the formula for Harry's charges is A + (B x no. of minutes), we can set up an equation:$19.05 = A + 48BBy solving any two of these equations simultaneously, we can find A (the fixed charge for access to internet) and B (the charge per minute).Subtracting Harry's equation from Kay's equation:$20.25 - $19.05 = 56B - 48B$1.2 = 8BB = $1.2/8B = $0.15Now we can substitute the value of B into any equation and solve it for A.Using Jay's equation:$17.40 = A + 37($0.15)$17.40 = A + $5.55A = $17.40 - $5.55 A = $11.85Based on the calculations, A (the fixed charge for access to internet) is $11.85, and B (the charge per minute) is $0.15. Hence, the correct formula for the cafe's internet charges is option D) $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. They manipulate variables to determine the causal relationship between the intervention and the outcomes.In an observational study, the treatment group is not subject to any intervention or change. Instead, researchers observe and analyze the existing behavior or characteristics of the participants to draw conclusions. Observational studies are more focused on observing and describing relationships rather than establishing causality.Therefore, Option A (experiment; observational study) is the correct choice that appropriately describes the distinction between the two types of studies.