Free Scientific Reasoning MCQs with Answers

311. The atmosphere is made up of 4 distinct layers: the troposphere, stratosphere, mesosphere, and thermosphere. Different types of clouds form in the different layers depending on the pressure in the atmosphere and the ambient temperature. The cloud types include nimbus, stratus, cumulus, and cirrus. Figure 1 shows the location of the barriers of the atmosphere when the temperature and pressure are at an ideal condition for cloud formation. It also shows the different types of clouds formed at the different levels. Note: Clouds are formed mostly of water crystals, but can also contain particles of rock and dust. If pressure of 7 psi were sustained within the atmosphere, according to fig 1, which of the following types of clouds would likely form?

• A. Cirrus
• B. Cumulus
• C. Nimbas
• D. Stratus

Explanation: At a pressure of 7 psi, Figure 1 shows that cloud formation will most likely occur in the stratosphere. According to Figure 1, clouds that form in the stratosphere are stratus clouds. This information best supports answer choice D.

312. Alcohols are carbon compounds containing a hydroxyl (OH) group. Alkenes are carbon compounds containing at least 1 carbon-carbon double bond (C=C). Dehydration (removal of H2O) of Alcohol W in the presence of phosphoric acid (H3PO4) produces H2O and a mixture of 4 alkenes (Alkenes 1-4) that each contain only 1 C=C bond: Dehydration of each of 3 other alcohols (Alcohols X, Y, and Z) produces H2O and 2 or more of Alkenes 1-4. Stu- dents studied the dehydration of each of these 4 alcohols, which are all liquids at 25°C. Which of the following statements gives the most likely reason that the test tube was cooled in ice water, as shown in Figure 1? The test tube was most likely cooled in ice water to more readily:

• A. Condense the liquid produced.
• B. Condense the vapour produced.
• C. Evaporate the liquid produced.
• D. Evaporate the vapour produced.

Explanation: Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporisation. A lower temperature is needed to reverse evaporation, this is the correct answer.

313. A bar magnet and a solenoid are kept beside each other. In which of the following cases current will not be produced?

• A. When the magnet is moving towards the solenoid
• B. When the solenoid is moving towards the magnet
• C. When both magnet and solenoid is moving in the same direction with the same speed
• D. When both magnet and solenoid is moving in the opposite direction with the same speed

Explanation: When both magnet and solenoid are moving in the same direction with the same speed, there is no relative motion between the bar magnet and solenoid. Therefore, no current is produced in such cases.

314. During a demonstration, a teacher placed 20 mL of water, 10 mL of isopropyl alcohol (IPA), and 1 drop of blue food coloring into a test tube, capped the test tube, and inverted it 6 times. Next, she added 7 g of ammonium sulfate (AS), an ionic solid, to the test tube, capped the test tube, and vigorously shook it for 10 sec. Then, over the 15 sec period immediately following the shaking, the mix- ture in the test tube completely separated into 2 distinct liquid layers (see figure). The teacher asked each of 4 students to provide an explanation for what occurred in the test tube over the 15 sec period. Student 1 Over the 15 sec, the mixture separated into 2 layers because IPA is denser than water. The water layer was on top, and the IPA layer was on the bottom. The AS dissolved in the IPA only, because AS breaks apart into neutral molecules when dissolved in IPA. Blue food colouring is polar, so it dissolves in the water only. Student 2 Over the 15 sec, the mixture separated into 2 layers because water is denser than IPA. The IPA layer was on top, and the water layer was on the bottom. The AS dis- solved in the water only, because AS breaks apart into neutral molecules when dissolved in water. Blue food colouring is polar, so it dissolves in the IPA only. Based on the figure, 5 see after the shaking, would the contents of the test tube have been better classified as a heterogeneous mixture or a homogeneous mixture?

• A. Heterogeneous, because the contents of the test tube varied in composition from one region to another.
• B. Heterogeneous, because the contents of the test tube were uniform in composition throughout.
• C. Homogeneous, because the contents of the test tube varied in composition from one region to another.
• D. Homogeneous, because the contents of the test tube were uniform in composition throughout.

Explanation: There are two types of mixtures: heterogeneous and homogeneous. Heterogeneous mixtures have visually distinguishable components, while homogeneous mixtures appear uniform throughout. The most common type of homogenous mixture is a solution, which can be a solid, liquid, or gas.

315. The following is a diagram of a sarcomere. How do the labelled parts change during muscle contraction?

• A. "D" shortens
• B. "C" stays the same
• C. "B" shortens
• D. Two "A"s move further away

Explanation: A sarcomere is defined as the distance between two consecutive Z discs or Z lines; when a muscle contracts, the distance between the Z discs is reduced. The H zone-the central region of the A zone-contains only thick filaments and is shortened during contraction. This is correct. D is the sarcomere, a represents Z line, b represents A zone, c represents z disc.

316. Study the following graph and answer the question. For which of the following pairs of years the total exports from the three Companies together are equal?

• A. 1995 and 1998
• B. 1996 and 1998
• C. 1997 and 199
• D. 1995 and 1996

Explanation: In 1995, the total exports were 220 and similarly, in 1996, the total exports were 220 as well. This option is the correct one as they both have equal number of exports.

317. Tollen's reagent, Ag+, is an oxidation agent. What are the products of Tollen's reagent reaction with the following molecule? Choose 1 answer:

• A. Propanol and Ag+
• B. Propanoic acid and Ag+
• C. Propanol and Ag
• D. Propanoic acid and Ag

Explanation: This is the correct option as it suggests that propionaldehyde forms propionic acid and Ag+ is reduced to Ag.

318. Passage I The figure below is a pedigree that shows the inheritance of a trait, Trait G, in a family. The presence of Trait G in an individual is determined entirely by Gene G. Gene G has 2 alleles: G, which is dominant, and g, which is recessive. Each individual represented in the pedigree was assigned a number (shown below the symbol for the individual) for reference. Scientists determined that the Gene G genotype of Individual 20 is gg and that the Gene G genotype of Individual 21 is Gg. Based on this information, the scientists concluded that Trait G is a recessive trait. Based on the figure, the 2 individuals in which of the following pairs most likely have the greatest genetic similarity across their genomes?

• A. Individual 3 and Individual 4
• B. Individual 12 and Individual 13
• C. Individual 16 and Individual 24
• D. Individual 18 and Individual 21

Explanation: The best answer is B. In order to answer this item, the examinee must know that the more closely related two individuals are to each other, the greater the genetic similarity is likely to be. According to the figure, Individuals 12 and 13 are sisters and would likely have the greatest genetic similarity.

319. Passage I The figure below is a pedigree that shows the inheritance of a trait, Trait G, in a family. The presence of Trait G in an individual is determined entirely by Gene G. Gene G has 2 alleles: G, which is dominant, and g, which is recessive. Each individual represented in the pedigree was assigned a number (shown below the symbol for the individual) for reference. Scientists determined that the Gene G genotype of Individual 20 is gg and that the Gene G genotype of Individual 21 is Gg. Based on this information, the scientists concluded that Trait G is a recessive trait. Suppose that Individual 23 and Individual 24 have 4 biological children. Based on the figure, how many of the children, if any, have Trait G?

• A. 0
• B. 1
• C. 3
• D. 4

Explanation: The best answer is D. In order to answer this item, the examinee must know how to work a genetic cross. According to the figure, both Individuals 23 and 24 have Trait G. According to the passage, Trait G is recessive. It follows that Individuals 23 and 24 both have the gg genotype and that all their children will also have the gg genotype. All their children will therefore have Trait G.

320. Predation is an interaction between individuals of 2 species in which one is harmed (the prey), and the other is helped (the predator). Predation can occur among plants and animals as well as between plants and animals. Some biologists contend that herbivores, or plant eaters, are predators. Table 1 indicates some characteristics and examples of certain predators. According to information in the passage, the number of prey consumed in an ecosystem is dependent on:

• A. the natural balance of the ecosystem.
• B. the total number of predators that die because of predation.
• C. the type of parasites available in the ecosystem.
• D. the number of predators present and the number of prey present.

Explanation: The best answer is D. The passage states that "the number of prey consumed depends on the number of prey present as well as the number of predators present." The other answer choices are not supported by the passage.