Nursing Elites

1. In a single displacement reaction, one element takes the place of another element in a compound. Which of the following is an example?

• A. 2H2 + O2 -> 2H2O
• B. Zn + 2HCl -> ZnCl2 + H2
• C. CaCO3 -> CaO + CO2
• D. CH4 + 2O2 -> CO2 + 2H2O

Correct answer: B

Rationale: In a single displacement reaction, one element replaces another element in a compound. Option B, 'Zn + 2HCl -> ZnCl2 + H2,' is an example of a single displacement reaction where zinc (Zn) replaces hydrogen (H) in hydrochloric acid (HCl) to form zinc chloride (ZnCl2) and hydrogen gas (H2). The other options do not involve one element displacing another in a compound. Option A is a synthesis reaction, option C is a decomposition reaction, and option D is a combustion reaction. Therefore, option B is the correct answer as it demonstrates the concept of single displacement reactions.

2. The largest bone in the human body is the:

• A. Femur (thigh bone)
• B. Tibia (shin bone)
• C. Humerus (upper arm bone)
• D. Scapula (shoulder blade)

Correct answer: A

Rationale: The correct answer is A: Femur (thigh bone). The femur is the longest and strongest bone in the human body, located in the thigh region. It plays a crucial role in supporting the body's weight and facilitating movement. The tibia (B) is commonly known as the shin bone and is located below the femur. The humerus (C) is the upper arm bone, and the scapula (D) is the shoulder blade. However, neither of these bones is the largest in the human body. Understanding the anatomy of the skeletal system is essential for identifying the largest bone in the body, which is the femur.

3. What type of reaction is represented by the following equation: Fe2O3 (s) + 3H2 (g) -> 2Fe (s) + 3H2O (g)

• A. Combustion
• B. Decomposition
• C. Single displacement
• D. Redox reaction

Correct answer: D

Rationale: The given equation involves a transfer of electrons from iron oxide (Fe2O3) to hydrogen gas (H2), resulting in the formation of iron (Fe) and water (H2O). This transfer of electrons indicates a redox reaction, where oxidation and reduction occur simultaneously. In this case, iron is reduced from a higher oxidation state in Fe2O3 to a lower oxidation state in Fe, while hydrogen is oxidized from its elemental state in H2 to form water. Therefore, the correct answer is D: Redox reaction.

4. Which hormone primarily triggers ovulation in the female menstrual cycle?

• A. Estrogen
• B. Progesterone
• C. Luteinizing hormone (LH)
• D. Follicle-stimulating hormone (FSH)

Correct answer: C

Rationale: The correct answer is C: Luteinizing hormone (LH). LH is the hormone responsible for triggering ovulation in the female menstrual cycle. During the menstrual cycle, LH surge occurs around day 14, which stimulates the release of a mature egg from the ovary. This surge in LH is crucial for the rupture of the mature follicle and the release of the egg, marking the onset of ovulation. Estrogen and progesterone play important roles in regulating the menstrual cycle, but LH specifically triggers ovulation by signaling the release of the egg from the ovary.

5. What is the name of the regulatory region in a gene that controls its expression?

• A. Exon
• B. Intron
• C. Promoter
• D. Enhancer

Correct answer: C

Rationale: Rationale: A) Exon: Exons are the coding regions of a gene that are transcribed into mRNA and eventually translated into proteins. Exons do not regulate gene expression. B) Intron: Introns are non-coding regions of a gene that are removed during RNA processing and do not play a direct role in controlling gene expression. C) Promoter: The promoter is a regulatory region located at the beginning of a gene that initiates the process of transcription by binding transcription factors and RNA polymerase. It plays a crucial role in controlling gene expression. D) Enhancer: Enhancers are regulatory regions that can be located far from the gene they regulate and can increase the transcription of a gene. While enhancers are important for gene expression, the specific region that controls gene expression is the promoter. Therefore, the correct answer is C) Promoter, as it is the regulatory region in a gene that controls its expression by initiating transcription.

6. A ball is thrown horizontally off a cliff. Which of the following forces is responsible for its downward motion?

• A. The force of throwing
• B. Normal force from the air
• C. Tension force from the string (if used)
• D. Gravitational force

Correct answer: D

Rationale: The gravitational force is responsible for the downward motion of the ball. When the ball is thrown horizontally off a cliff, the only force acting on it in the vertical direction is the force of gravity, which pulls the ball downward towards the ground. The other forces mentioned (force of throwing, normal force from the air, tension force from the string) do not contribute to the ball's downward motion in this scenario.

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