Nokea
What is the oxidation state of carbon in CH4?
- A. +1
- B. -1
- C. +2
- D. -4
Correct Answer: D
Rationale: In CH4 (methane), carbon is bonded to four hydrogen atoms. Hydrogen has an oxidation state of +1. Since the overall charge of CH4 is 0, the oxidation state of carbon must be -4 to balance the charges. Each hydrogen contributes an oxidation state of +1, resulting in a total of +4 from hydrogen atoms. To achieve a total oxidation state of 0 for the molecule, carbon must have an oxidation state of -4 to offset the contribution from hydrogen. Therefore, the correct answer is -4. Choices A, B, and C are incorrect: +1 is the oxidation state of hydrogen, -1 is not the oxidation state of carbon in methane, and +2 is not the correct oxidation state of carbon in CH4.
You may also like to solve these questions
Passive transport does not require energy input from the cell. Which of the following is an example of passive transport?
- A. Active transport of ions across a membrane
- B. Diffusion of small molecules across a concentration gradient
- C. Movement of large molecules using vesicles
- D. Endocytosis of particles into the cell
Correct Answer: B
Rationale: Passive transport refers to the movement of molecules across a cell membrane without the input of energy. Diffusion of small molecules across a concentration gradient is a classic example of passive transport, as it occurs spontaneously from an area of high concentration to an area of low concentration. Active transport (option A) requires energy input in the form of ATP to move substances against their concentration gradient. Movement of large molecules using vesicles (option C) involves processes like endocytosis and exocytosis that require energy in the form of ATP. Endocytosis of particles into the cell (option D) is an active process that requires energy expenditure by the cell to engulf and internalize extracellular substances.
Which muscular chamber of the heart receives blood from the body and pumps it to the lungs?
- A. Right atrium
- B. Left atrium
- C. Right ventricle
- D. Left ventricle
Correct Answer: A
Rationale: The correct answer is the right atrium. The right atrium receives deoxygenated blood from the body through the superior and inferior vena cava. It then pumps this deoxygenated blood to the lungs via the pulmonary artery for oxygenation. The left atrium receives oxygenated blood from the lungs and pumps it to the left ventricle. The right ventricle receives oxygen-poor blood from the right atrium and pumps it to the lungs. The left ventricle receives oxygenated blood from the left atrium and pumps it to the rest of the body.
How is power related to work and time?
- A. Power = Work · Time
- B. Power = Work Time
- C. Power = Work + Time
- D. Power = Work - Time
Correct Answer: A
Rationale: Power is defined as the rate at which work is done or the amount of work done per unit of time. The correct formula to relate power, work, and time is Power = Work · Time. This formula shows that power is calculated by dividing the amount of work done by the time taken to do that work, indicating the rate at which work is being done. Choice B (Power = Work Time) is incorrect because multiplying work and time does not yield a measure of power. Choice C (Power = Work + Time) is incorrect as adding work and time does not define power. Choice D (Power = Work - Time) is also incorrect because subtracting work and time does not relate to the concept of power.
Which of the following hormones is produced by the adrenal medulla and prepares the body for a stressful situation?
- A. Testosterone
- B. Cortisol
- C. Epinephrine (adrenaline)
- D. Growth hormone
Correct Answer: C
Rationale: The correct answer is C: Epinephrine (adrenaline). Epinephrine is produced by the adrenal medulla and is responsible for preparing the body for a stressful situation. It increases heart rate, dilates airways, and mobilizes energy stores to help the body respond to a fight-or-flight scenario. Testosterone (Choice A) is a sex hormone produced by the testes in males and in smaller amounts by the ovaries in females, not by the adrenal medulla. Cortisol (Choice B) is a stress hormone produced by the adrenal cortex, not the adrenal medulla. Growth hormone (Choice D) is produced by the pituitary gland and is involved in growth, metabolism, and various bodily functions, not by the adrenal medulla.
What is the medical term for a urinary tract infection (UTI)?
- A. Nephritis
- B. Cystitis
- C. Urethritis
- D. All of the above
Correct Answer: B
Rationale: The medical term specifically used to refer to a urinary tract infection (UTI) that affects the bladder is cystitis. Nephritis refers to inflammation of the kidneys, and urethritis refers to inflammation of the urethra. As such, cystitis is the correct term for a UTI, making choice B the right answer. Choices A, C, and D are incorrect because they refer to different conditions affecting the urinary system.