Free Scientific Reasoning MCQs with Answers

261. Al-Jolson Airways runs a scheduled flight from Marseilles to Cairo, stopping at Palermo and Benghazi, every day. The plane takes off from Marseille at 08:00 and arrives at Palermo an hour later. After a 10-minute stop, it takes off again and then lands at Benghazi at 10:00, where it takes 10 minutes to refuel before taking off for Cairo. It finally lands in Cairo at 11:30. The aeroplane normally flies at 600 km/h, but on today's flight the pilot encountered turbulence and had to slow down to 500 km/h for 15 minutes. The plane was delayed in the approach to Cairo and had to circle at 300 km/h for 10 minutes before landing. Which of the following graphs best represents the airplane's speed during the journey?

• A. Option A
• B. Option B
• C. Option C
• D. Option D

Explanation: The correct graph should reflect the initial constant speed of 600 km/h, a reduction to 500 km/h for 15 minutes due to turbulence, and a final reduction to 300 km/h while circling for 10 minutes before landing. Option B accurately represents these speed changes. Options A, C, and D fail to capture one or more of these critical details, such as speed reductions or circling periods.

262. Two the edges of Mae's rectangular lawn measure 7 metres.Which one of the following further pieces of information about Mae's lawn would not be sufficient by itself to determine how long the other two sides are?

• A. The area of the lawn in square metres is numerically equal to its perimeter in metres
• B. The length of the lawn is 2.5 times its width
• C. The mean of the length and the width of the lawn is 4.8 metres
• D. The perimeter of the lawn is 19.2 metres

Explanation: The correct answer is Option D. Knowing only the perimeter does not provide enough information to determine the exact dimensions of the lawn. A rectangle can have multiple length and width combinations that result in the same perimeter, so without additional information, the dimensions cannot be uniquely determined.Option A gives a specific equation that relates the area and perimeter, which can be used to solve for the dimensions. Option B provides a ratio between the length and width, allowing you to find both dimensions when one is known. Option C provides the mean of the length and width, which can be combined with the known side measurement to determine the other side.

263. Abdullah needs to take a bus to Lahore, which leaves once an hour from his hometown. Nobody in his family knows at exactly how many minutes past the hour the bus is scheduled to depart.Aisha is sure that the number is such that, if it were divided by 3. the remainder would be 2. Sharif is certain that the number is such that, divided by 4, there would be a remainder of 3. Abdullah's father has no doubt that the number of minutes is a multiple of 5.Assuming that they have all given correct information, at how many minutes past the hour does the bus depart?

• A. 5
• B. 15
• C. 35
• D. 45

Explanation: The correct answer is 35 minutes past the hour. This number satisfies all the given conditions: When 35 is divided by 3, it leaves a remainder of 2, which matches Aisha's statement. When 35 is divided by 4, it leaves a remainder of 3, which matches Sharif's statement. Finally, 35 is a multiple of 5, which matches Abdullah's father's statement. The other options do not meet all these conditions simultaneously.

264. A child is playing a game by placing four straight sticks on the grand.She scores 1 point for every crossing point made. She cannot break any of the sticks.What is the largest number of points that she can score

• A. 4
• B. 5
• C. 6
• D. 7

Explanation: The largest number of crossing points that can be achieved by placing four straight sticks is 6. Each new stick can intersect with all the previous sticks already laid down. The first stick has no intersections, the second can intersect the first, the third can intersect the first and second, and the fourth can intersect the first three. This results in 0 + 1 + 2 + 3 = 6 intersections. Option A (4) and Option B (5) do not utilize the full potential of intersections. Option D (7) is not possible with only four sticks without breaking any, which is against the rules of the game.

265. The yeast I use to make bread doubles in size overnight, but I take a fixed weight away each day.Which one of the following plots could not show the weight of yeast on consecutive days after the ixed weight has been removed?

• A. A
• B. B
• C. C
• D. D

Explanation: Option B is the correct answer because it exhibits an inconsistent pattern not compatible with the systematic doubling and subtraction process described. For a plot to be incorrect, it must represent a pattern that is impossible given the scenario. Options A, C, and D could potentially depict the yeast's weight changes over time, as they can illustrate a regular pattern of growth (doubling) and reduction (fixed weight removal). Option A shows a consistent decrease, Option C depicts a steady pattern, and Option D aligns with the expected growth and reduction cycle.

266. I received the following email:I have only $2250 but I want to send two messages to the largest number of addresse worldwide. What is the largest number of addresses I can contact?

• A. 123,000,000
• B. 205,000,000
• C. 2,230,000,000
• D. 32,000,000

Explanation: The correct answer is 205,000,000. To solve this, you need to consider the budget of $2,250 and the cost per message. By dividing the budget by the cost per message, you can determine the maximum number of messages that can be sent. Option B aligns with this calculation and represents the correct answer. Options A, C, and D either underestimate or overestimate the number of messages based on the given budget, making them incorrect choices.

267. A dice is numbered from 1 to 6 in different ways. If 1 is adjacent to 2, 4, and 6, then which of the following statements is necessarily true?

• A. 2 is opposite to 6
• B. 1 is adjacent to 3
• C. 3 is adjacent to 5
• D. 3 is opposite to 5

Explanation: In a standard six-sided die, each face has a number from 1 to 6. Given that 1 is adjacent to 2, 4, and 6, and between 3 and 5 one of them will be adjacent to 1 and one will be on the opposite side. Since in any case the number opposite to one will have one opposite face already present face 1 so 3 and 5 will be adjacent to each other.

268. 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, 2, and 3 only
• B. 1 and 3 only
• C. 1 and 4 only
• D. 2 and 3 only

Explanation: Statements 1,3 are correct. Based on the information provided, the correct statements about this chemical reaction are: The cleaning solution is acidic. The pH of the reacting solution will go down as the reaction proceeds. Explanation: The cleaning solution being acidic is likely the reason why it can dissolve limescale (CaCO3). Acidic solutions can react with and dissolve calcium carbonate, breaking it down into soluble products. The effervescence (fizzing) occurs due to the reaction between the acidic solution and calcium carbonate. When an acid reacts with a carbonate compound like CaCO3, it releases carbon dioxide (CO2) gas, which causes the fizzing. As the reaction proceeds and the acidic solution reacts with the limescale (CaCO3), it will produce carbon dioxide gas and water. The presence of carbon dioxide in the solution can lead to the formation of carbonic acid (H2CO3) by combining with water. This carbonic acid can further contribute to the acidic nature of the solution, leading to a decrease in pH. However, statement 4 cannot be determined based on the information provided. The given information does not mention the specific salt produced in the reaction, nor does it provide any details about its solubility compared to CaCO3.

269. The price for hiring a car is determined by the number of days for which it is to be hired and the number of people who will be using it. The table below shows the prices for groups of up to 5 people hiring cars for up to 7 days. Patrick is part of a group of 5 people on a holiday for 5 days. They will be going on outings each day, and had planned to hire one car for all of them for all 5 days. However, two of the group of people will only be there for the first 3 days, so an alternative is to hire one car for this period and another for the final two days. What will be the difference if they choose this alternative?

• A. It will be $5 cheaper
• B. It will be $2 cheaper
• C. It will be $2 more expensive
• D. It will be $5 more expensive

Explanation: Cost of car for 5 people for 5 days=$14Cost of car for 5 people for 3 days=$10Cost of car for 3 people for 2 days=$6Alternative Cost= Cost of car for 5 people for 3 days + Cost of car for 3 people for 2 days = $10 + $6 = $16Alternative Cost - Actual Cost = $16 - $14 = $2If they choose the alternative, it will be $2 more expensive. Hence, the answer is option C.

270. 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 2 only
• B. 1 and 3 only
• C. 1 and 4 only
• D. 2 and 3 only
• E. 2 and 4 only
• F. 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.