Nokea
How many electrons are typically found in each shell of a neutral aluminum atom with 13 electrons in its electron cloud?
- A. 6 in the first shell, 7 in the second shell
- B. 2 in the first shell, 11 in the second shell
- C. 2 in the first shell, 8 in the second shell, 3 in the third shell
- D. 3 in the first shell, 5 in the second shell, 5 in the third shell
Correct Answer: C
Rationale: In a neutral aluminum atom with 13 electrons, the electron distribution typically follows the electron shell filling order based on the Aufbau principle. The first shell can hold a maximum of 2 electrons, the second shell can hold up to 8 electrons, and the third shell can hold up to 8 electrons as well. Therefore, the distribution would be 2 electrons in the first shell, 8 electrons in the second shell, and 3 electrons in the third shell, totaling 13 electrons. Choice A is incorrect as it exceeds the maximum number of electrons the shells can hold. Choice B is incorrect as it does not distribute the electrons correctly among the shells. Choice D is incorrect as it also does not distribute the electrons correctly among the shells.
You may also like to solve these questions
What is a rod-shaped structure that forms when a single DNA molecule and its associated proteins coil tightly before cell division?
- A. Centromere
- B. Chromatid
- C. Chromosome
- D. Gene
Correct Answer: C
Rationale: A chromosome is a rod-shaped structure that forms when a single DNA molecule and its associated proteins coil tightly before cell division. It contains the genetic material and is essential for cell division and replication. The centromere is a specific region of a chromosome that plays a role in cell division. A chromatid is one half of a duplicated chromosome, and a gene is a unit of heredity responsible for specific traits. Therefore, the correct answer is 'Chromosome' as it represents the entire condensed DNA molecule during cell division.
Where is the cervix located?
- A. Top of the uterus
- B. Top of the ovaries
- C. Bottom of the vagina
- D. Bottom of the uterus
Correct Answer: D
Rationale: The cervix is located at the bottom of the uterus, where it opens into the vagina. It serves as the passageway between the uterus and the vagina, playing a crucial role in childbirth and menstrual flow. Choice A ('Top of the uterus') is incorrect because the cervix is not located at the top of the uterus. Choice B ('Top of the ovaries') is incorrect as the cervix is not located near the ovaries. Choice C ('Bottom of the vagina') is incorrect as the cervix is not located at the bottom of the vagina, but rather at the bottom of the uterus.
What substance is required to drive the sliding filament process during muscle contraction?
- A. ATP
- B. Hormone
- C. Potassium
- D. Water
Correct Answer: A
Rationale: The substance required to drive the sliding filament process during muscle contraction is ATP (adenosine triphosphate). ATP provides the energy needed for muscle contraction by enabling the myosin heads to bind to actin and generate force. This energy release drives the sliding of the filaments, causing muscle fibers to contract. Hormones, potassium, and water do not directly drive the sliding filament process in muscle contraction. Hormones are signaling molecules that regulate various physiological processes but do not directly provide energy for muscle contraction. Potassium is an electrolyte important for nerve and muscle function but is not the primary driver of the sliding filament process. Water is essential for overall hydration and bodily functions but does not directly participate in the muscle contraction process.
Which of the following hormones would cause skin color to become darker?
- A. Follicle-stimulating
- B. Growth-stimulating
- C. Thyroid-stimulating
- D. Melanocyte-stimulating
Correct Answer: D
Rationale: The correct answer is D, Melanocyte-stimulating. Melanocyte-stimulating hormone (MSH) stimulates melanocytes in the skin to produce more melanin, leading to darker skin pigmentation. Choices A, B, and C are incorrect as Follicle-stimulating hormone (FSH) stimulates follicle growth in the reproductive system, Growth-stimulating hormone is a vague term not specific to any known hormone, and Thyroid-stimulating hormone (TSH) stimulates the thyroid gland to produce thyroid hormones, not affecting skin color pigmentation.
A person wakes up with a fever. The body begins its response to locate the origin of the problem and fix it. What type of feedback mechanism is this?
- A. Equal
- B. Negative
- C. Neutral
- D. Positive
Correct Answer: B
Rationale: This scenario describes a negative feedback mechanism. When the body detects a fever, it initiates responses to lower the temperature back to normal levels. Negative feedback mechanisms work to counteract changes and maintain homeostasis in the body. Choice A ('Equal') is incorrect as feedback mechanisms aim to restore balance, not maintain an equal state. Choice C ('Neutral') is incorrect as it does not describe the corrective nature of negative feedback. Choice D ('Positive') is incorrect as it would amplify the fever rather than regulate it.