1

Which of the following is an example of a heterogeneous mixture?

A

Saltwater

B

Air

C

Blood

D

Granite

E

Answer

D, Explanation: Granite is an example of a heterogeneous mixture because it consists of visibly different substances, such as various minerals, that are not uniformly distributed throughout the mixture. In contrast, options A (Saltwater), B (Air), and C (Blood) are examples of homogeneous mixtures where the components are uniformly distributed and indistinguishable at the macroscopic level.

Instruction

2

Which of the following is noble gas?

A

Oxygen

B

Helium

C

Nitrogen

D

Hydrogen

E

Answer

B, Explanation: Helium is a noble gas. Noble gases are a group of elements found in Group 18 of the periodic table and include helium, neon, argon, krypton, xenon, and radon. These gases are characterized by their very low reactivity due to their stable electron configurations. Options A (Oxygen), C (Nitrogen), and D (Hydrogen) are not noble gases.

Instruction

3

Which of the following statements accurately describes the role of catalysts in chemical reactions?

A

Catalysts increase the activation energy required for a reaction to occur.

B

Catalysts decrease the rate of a chemical reaction.

C

Catalysts are consumed in the reaction they catalyze.

D

Catalysts alter the equilibrium constant of a reaction.

E

Answer

C, Explanation: Catalysts are substances that increase the rate of a chemical reaction by providing an alternative reaction pathway with lower activation energy. Importantly, catalysts themselves remain unchanged at the end of the reaction and are not consumed. Option A is incorrect because catalysts lower the activation energy required for a reaction.

Instruction

4

Which of the following is an example of an exothermic reaction?

A

Burning of candles

B

Photosynthesis

C

Dissolving sugar in water

D

Melting of ice

E

Answer

A, Explanation: The burning of candle is an example of an exothermic reaction. In exothermic reactions, heat is released to the surroundings, resulting in an increase in temperature. Option B (Photosynthesis) is an endothermic reaction where energy is absorbed from the surroundings. Option C (Dissolving sugar in water) is also an endothermic process as it requires energy input. Option D (Melting of ice) is a phase change and does not involve a chemical reaction.

Instruction

5

Which of the following is Lewis acid?

A

HCL

B

NaOH

C

H2O

D

AlCl3

E

Answer

D, Explanation: AlCl3 (aluminum chloride) is a Lewis acid. A Lewis acid is a substance that can accept an electron pair. In the case of AlCl3, it can accept a pair of electrons from a Lewis base to form a coordinate covalent bond. Options A (HCl), B (NaOH), and C (H2O) are not Lewis acids; they are either Bronsted-Lowry acids or bases.

Instruction

6

Which of the following substances undergoes sublimation at room temperature and pressure?

A

Sodium chloride (NaCl)

B

Carbon dioxide (CO2)

C

Water (H2O)

D

Ethanol (C2H5OH)

E

Answer

B, Explanation: Carbon dioxide (CO2) undergoes sublimation at room temperature and pressure. Sublimation is the process by which a substance transitions directly from a solid phase to a gas phase without passing through the intermediate liquid phase.

Instruction

7

Which of the following is a characteristic property of acids?

A

Turn blue litmus paper red

B

Turn red litmus paper blue

C

Taste bitter

D

Have a pH above 7

E

Answer

A, Explanation: Turning blue litmus paper red is a characteristic property of acids. Acids are substances that release hydrogen ions (H+) when dissolved in water, leading to an increase in the concentration of H+ ions in the solution. This acidic solution turns blue litmus paper red.

Instruction

8

Which of the following is a common example of a base found in household products?

A

Vinegar

B

Lemon juice

C

Baking soda

D

Milk

E

Answer

C, Explanation: Baking soda (sodium bicarbonate) is a common example of a base found in household products. It is often used in cooking, cleaning, and as a leavening agent in baking. Options A (Vinegar), B (Lemon juice), and D (Milk) are acidic substances commonly found in households.

Instruction

9

Which of the following elements is commonly used in the manufacture of batteries?

A

Iron

B

Zinc

C

Copper

D

Aluminum

E

Answer

B, Explanation: Zinc is commonly used in the manufacture of batteries. Zinc-carbon batteries and alkaline batteries are examples of batteries that utilize zinc in their construction. Options A (Iron), C (Copper), and D (Aluminum) are not commonly used as primary elements in battery manufacturing processes.

Instruction

10

What is the primary greenhouse gas responsible for the enhanced greenhouse effect, leading to global warming?

A

Carbon monoxide (CO)

B

Methane (CH4)

C

Water vapor (H2O)

D

Nitrous oxide (N2O)

E

Answer

B, Explanation: Methane (CH4) is the primary greenhouse gas responsible for the enhanced greenhouse effect, leading to global warming. While carbon dioxide (CO2) is the most abundant greenhouse gas, methane has a much higher global warming potential per molecule. Methane is emitted from various sources, including agriculture (e.g., livestock digestion and rice cultivation), landfills, and fossil fuel production. Options A (Carbon monoxide), C (Water vapor), and D (Nitrous oxide) are also greenhouse gases, but methane has a greater impact on global warming due to its higher potency and shorter atmospheric lifetime.

Instruction