Free Scientific Reasoning MCQs with Answers

41. It takes longer to cook meat on mountainous regions. Why?

• A. The boiling point of water is lower at higher altitudes.
• B. Meat from mountainous animals is stronger than animals on the ground level.
• C. Pathogens and pollutants in urban cities cause the meat to rot a bit before we begin to cook it.
• D. None of the above

Explanation: Because water boils at a lower temperature at higher elevations, foods that are prepared by boiling or simmering will cook at a lower temperature, and it will take longer to cook. High altitude areas are also prone to low humidity, which can cause the moisture in foods to evaporate more quickly during cooking

42. Why are Air-Conditioning units (ACs) always installed on the upper side of a room?

• A. To prevent someone from bumping into them and hurting themselves
• B. So that the cool air can efficiently circulate and cool the entire room
• C. To set up convection currents to cool the room since the cool air is denser and settles down
• D. It's just a standard, you can place the units anywhere you like

Explanation: Air-conditioning units are installed on the upper side of a room to facilitate effective cooling through convection currents. Cool air emitted from the AC is denser and naturally descends, displacing the warmer, less dense air which rises. This sets up a convection current that helps in the efficient distribution of cool air throughout the room.Option A is incorrect because while safety is important, it's not the primary reason for positioning. Option B is incorrect as direct relief is not the main objective; it's about overall room cooling. Option D is incorrect because strategic placement is crucial for optimal performance and energy efficiency.

43. Why do cities nearer to a water body have relatively moderate weather conditions as compared to those away from water bodies?

• A. Water has a high specific heat capacity so does not heat up or cool down easily.
• B. Water reflects more light than buildings and land
• C. Water evaporates to give cloud cover
• D. Water extinguishes the Sun.

Explanation: The high heat capacity of water also explains why the temperatures of land near a body of water are more moderate. The high heat capacity of water keeps its temperature within a relatively narrow range, causing nearby coastal areas to also have a narrow daily and seasonal temperature range.

44. How does aquatic life survive freezing temperatures?

• A. Aquatic organisms produce antifreeze proteins that prevent their bodies from freezing.
• B. In water bodies, the top layer freezes, forming an insulating layer, allowing aquatic life to survive beneath it.
• C. Aquatic life migrates to warmer parts of the water body to escape freezing temperatures.
• D. They perish in winter but leave behind resilient eggs to hatch in spring.

Explanation: The correct answer is that only the top layer of a water body freezes, creating an insulating barrier that keeps the water below from freezing. This allows aquatic life to survive in the liquid water beneath the ice. The ice acts as a protective layer, trapping heat and maintaining a stable environment for organisms. Additionally, oxygen is trapped beneath the ice, allowing fish and other aquatic life to breathe. The other options are incorrect because: - Antifreeze proteins are not the primary survival method for most aquatic life. - Migration to warmer parts of a water body is not a typical behavior for aquatic organisms in response to freezing temperatures. - While some species lay eggs that survive winter conditions, most aquatic organisms do not rely on this strategy for population survival.

45. Why is the greenhouse effect given that name?

• A. The greenhouse effect is named for the environmental goal of planting more trees to combat global warming.
• B. The greenhouse effect is named because it describes the process by which greenhouse gases trap heat, similar to how a greenhouse's glass structure traps heat.
• C. The term was coined by a scientist who had a preference for the color green.
• D. None of the above options accurately describes the origin of the term 'greenhouse effect.'

Explanation: The term 'greenhouse effect' is used because Earth's atmosphere acts in a manner similar to a greenhouse. Just as the glass in a greenhouse allows sunlight to enter and prevents heat from escaping, greenhouse gases in the atmosphere trap heat, maintaining the planet's temperature. Option B correctly captures this analogy. Option A confuses the term with environmental actions. Option C incorrectly attributes the term to personal preferences, and Option D is invalid because Option B is a correct explanation.

46. Why should you not stand close to a fast-moving train?

• A. The fast-moving train creates a strong air pressure that can pull you towards it, risking serious injury.
• B. The train's speed might make you feel dizzy, potentially causing you to faint.
• C. Objects falling from the train could hit you due to the train's high velocity, causing injury.
• D. There is no real danger; it's just a safety guideline.

Explanation: When you stand close to a fast-moving train, the train's rapid movement creates a lower air pressure between the train and the person compared to the other side. According to Bernoulli's principle, this pressure difference results in a force that can pull a person towards the train, leading to a risk of accidents and injuries. Option A correctly identifies the primary danger associated with standing too close to a fast-moving train. Option B is incorrect because dizziness is not the main concern. Option C is incorrect as the falling objects are not the primary risk. Option D is incorrect because it ignores the real danger posed by air pressure differences.

47. How does soap work to clean our hands?

• A. The slippery nature of the soap causes the germs to slip off
• B. The soap traps germs and dirt and is washed off with them
• C. The soap disintegrates grease on the skin due to its non-polar tail
• D. The soap produces free radicals which destroy the germs on our hands

Explanation: Soap works through its molecular structure, which consists of a hydrophobic (non-polar) tail and a hydrophilic head. The non-polar tails bind to oils and grease on the skin, breaking them down. The hydrophilic heads allow these particles to be rinsed away with water. This is why Option C is correct.Option A is incorrect because slipperiness is not a factor in removing germs.Option B is incorrect as soap does not simply trap dirt and germs; it interacts chemically with them.Option D is incorrect because soap does not produce free radicals.

48. We assemble the following apparatus for a reaction where a solid is:

• A. Heated in a vacuum
• B. Distilled from a solution
• C. Reacts with a liquid
• D. Melted

Explanation: The assembled apparatus is specifically used for a reaction where a solid reacts with a liquid, producing a gas that is subsequently collected. This setup aligns with option C, 'Reacts with a liquid.' Option A, 'Heated in a vacuum,' is incorrect as it involves preventing oxidation without involving a liquid reaction. Option B, 'Distilled from a solution,' does not fit as distillation separates substances based on boiling points without a gas-producing reaction. Option D, 'Melted,' is incorrect because melting does not involve a chemical reaction to produce gas.

49. Ignoring air resistance, at what angle from the ground should a footballer hit a football to achieve maximum range?

• A. 30 degrees
• B. 45 degrees
• C. As less of an angle as possible
• D. 90 degrees

Explanation: The range (x) for an angle theta is given by the following: For x to be the largest, cos θ sinθ should be the largest. This is true for θ=45 degrees.

50. The figure represents a ball being swung around with a string. At what position of the ball should the string be released in order for the ball to hit the target?

• A. 1
• B. 2
• C. 3
• D. 4

Explanation: The ball moves in a tangential direction when released because the centripetal force is no longer acting on it. At position 3, the tangent is aimed directly at the target, making it the correct release point. Positions 1, 2, and 4 all result in tangents that miss the target due to their misalignment.