Free Scientific Reasoning MCQs with Answers

91. A certain electron travels within a conductor. The path of electron for a short time interval is shown below. Which of these best represents the path the electron would have travelled if it was experiencing an additional constant force towards left? The dotted line shows the path.

• A. A
• B. B
• C. C
• D. D

Explanation: The correct path is shown in this diagram. In the presence of an electric field inside the conductor, free electrons are accelerated. The given option is correct.

92. 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.What was the most likely purpose of the sand bath shown in Figure 1 ?

• A. To partially cool the test tube
• B. To evenly distribute heat to the flask
• C. To provide sand as a reactant in the dehydration reaction
• D. To provide sand as a surface onto which the vapours would condense

Explanation: The sand bath spreads the heat out so that the flask is heated evenly. This reduces the chance of the flask breaking and ensures that there are no hot spots in the reaction mixture which could lead to excessive charring, for example.

93. 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. Students 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 produce
• 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 vaporization. A lower temperature is needed to promote condensation of vapors into liquid; hence, B is the correct answer.

94. 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 the magnet and solenoid are moving in the same direction with the same speed
• D. When both magnet and solenoid are moving in opposite directions 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.

95. Two current-carrying wires with the same current flowing through them are placed one above the other as shown in the figure. If the wires form four regions A, B, C, and D as shown, which region has the strongest magnetic field out of the page?

• A. A
• B. B
• C. C
• D. D

Explanation: Since the two currents are the same, the magnitude of the magnetic field produced by each current-carrying wire will be the same in each region. Let the two current directions be marked in blue and red as shown. Then, the direction of the magnetic field in each of the regions due to the current will be as mentioned.Magnetic fields are the same, and those directed oppositely will cancel out.Hence, the net magnetic field will be maximum in regions A and D. The magnetic field due to both the current-carrying wire Is directed out of the page in region A.region A has the strongest magnetic field out of the page.

96. When the given figure is folded to form a cube then which face is opposite to the face with 2?

• A. 3
• B. 1
• C. 4
• D. 6

Explanation: Once the cube is folded the faces opposite to each other, are 2 and 1, 4 and 5, 3 and 6. Therefore, this is not the answer.

97. Mohan is older than Prabir. Suresh is younger than Prabir. Mihar is older than Suresh, but younger than Prabir. Who among the four is the youngest?

• A. Prabir
• B. Mihir
• C. Mohan
• D. Suresh

Explanation: The order can be followed as suchMohan > Prabir > Mihir > SureshHence, the correct answer is "Suresh".

98. 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 1Over 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 2Over 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.

99. Suppose that 20 mL of water and 20 mL of IPA are poured into a beaker, mixed, and then allowed to settle. Based on Student 2's explanation, the resulting con- tents of the beaker would best be represented by which of the following diagrams?

• A. A
• B. B
• C. C
• D. D

Explanation: Following the conditions mentioned in the question the correct answer is this one, focus closely on 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.

100. What will come at the place of the question mark? 3, 7, 23, 95, ?

• A. 62
• B. 128
• C. 479
• D. 575

Explanation: The sequence follows a pattern where each term is generated by multiplying the previous term by an increasing integer and then adding another increasing integer. Specifically, the operations are:3 x 2 + 1 = 77 x 3 + 2 = 2323 x 4 + 3 = 9595 x 5 + 4 = 479Thus, Option C (479) correctly follows this pattern. The other options do not adhere to this rule of sequential multiplication and addition, leading to incorrect answers.