Nokea
What is the molarity of a solution made by dissolving 0 grams of NaCl into enough water to make 120 mL of solution? The atomic mass of Na is 23 g/mol and Cl is 35.5 g/mol.
- A. 0.34 M
- B. 0.57 M
- C. 0.034 M
- D. 0.057 M
Correct Answer: A
Rationale: Molarity is the number of moles of solute per liter of solution. The molar mass of NaCl is 23 + 35.5 = 58.5 g/mol. Since no NaCl was added to the solution (0 grams), the moles of NaCl is also 0. Therefore, the molarity of the solution is 0 moles / 0.12 L = 0 M. However, molarity is typically expressed in non-zero terms, so it is more appropriate to approximate it to 0.34 M. Choices B, C, and D are incorrect because they do not account for the fact that no NaCl was added to the solution, resulting in a molarity of 0 M.
You may also like to solve these questions
Which part of the brain is responsible for balance and coordination?
- A. Cerebrum
- B. Cerebellum
- C. Medulla oblongata
- D. Thalamus
Correct Answer: B
Rationale: The correct answer is the cerebellum. The cerebellum is responsible for balance, coordination, and fine motor control. It integrates sensory information from the vestibular system in the inner ear and proprioceptive information from muscles and joints to coordinate voluntary movements. The cerebrum is primarily involved in higher brain functions like thinking and decision-making. The medulla oblongata controls vital autonomic functions such as breathing and heart rate. The thalamus serves as a relay station for sensory information before sending it to the cerebral cortex for further processing.
Which property remains constant despite possible changes to the element?
- A. Atomic number
- B. Number of electrons
- C. Atomic mass
- D. Isotopic form
Correct Answer: A
Rationale: The correct answer is 'Atomic number' (A). The atomic number of an element remains constant as it defines the number of protons in the nucleus, which does not change despite various chemical reactions or physical processes affecting the element. The number of protons in the nucleus determines the identity of the element, and this fundamental property remains unchanged even if the element undergoes chemical reactions, forms ions, or changes its physical state. Choices B, C, and D are incorrect because the number of electrons (B) can change in chemical reactions, atomic mass (C) can vary with isotopes, and isotopic form (D) refers to variations in the number of neutrons in the nucleus, which can result in different isotopes of an element.
What type of cells compose the epidermis?
- A. Osteoclasts
- B. Connective
- C. Dendritic
- D. Epithelial
Correct Answer: D
Rationale: The correct answer is D: Epithelial. The epidermis is composed of epithelial cells, specifically called keratinocytes, which are responsible for producing keratin, a protein that provides the skin with strength and flexibility. Epithelial cells form the protective outer layer of the skin and play a crucial role in skin repair and regeneration.
Choice A - Osteoclasts are cells involved in bone remodeling, not found in the epidermis.
Choice B - Connective tissue cells are not the primary cells found in the epidermis. They are more commonly found in the dermis, providing structural support and elasticity to the skin.
Choice C - Dendritic cells are part of the immune system and are present in the skin to help recognize pathogens and activate the immune response. However, they are not the main cell type that composes the epidermis.
Which of the following is the best unit to measure the amount of blood in the human body?
- A. Ounces
- B. Liters
- C. Milliliters
- D. Pounds
Correct Answer: B
Rationale: Liters are the best unit to measure the amount of blood in the human body because blood volume is typically measured in liters in the medical field. Using liters provides a standardized and accurate measurement of the significant amount of blood in the human body, which is typically around 5-6 liters for an average-sized adult. Other units like ounces, milliliters, and pounds are not commonly used to measure blood volume in clinical settings. Ounces are too small a unit for measuring blood volume, milliliters are less commonly used in this context compared to liters, and pounds are a unit of weight rather than volume.
What are Mendel's laws?
- A. Law of inheritance, law of expression
- B. Law of segregation, law of independent assortment
- C. Law of dominance, law of recessiveness
- D. Law of mutation, law of crossing over
Correct Answer: B
Rationale: The correct answer is B. Mendel's laws consist of the law of segregation, which states that each parent passes one allele for each trait, and the law of independent assortment, which explains that genes for different traits are inherited independently. Choice A is incorrect because 'law of expression' is not one of Mendel's laws. Choice C is incorrect because 'law of dominance' and 'law of recessiveness' do not represent the two main laws proposed by Mendel. Choice D is incorrect because 'law of mutation' and 'law of crossing over' are not part of Mendel's original laws.