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 0 gmol and

ATI TEAS 7

ATI TEAS Science Questions

1. 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.

2. What is the difference between a pure substance and a mixture?

A. Pure substances have a fixed composition, mixtures don't.
B. Mixtures have a fixed composition, pure substances don't.
C. Pure substances can be in any state, mixtures are not always solids.
D. Pure substances are always elements, mixtures are always compounds.

Correct answer: A

Rationale: Pure substances have a definite and constant composition, meaning they are made up of only one type of atom or molecule with fixed proportions. This composition does not vary. On the other hand, mixtures are composed of two or more substances physically combined. The components of a mixture can be present in varying proportions, leading to a variable composition. Choice A is correct as it accurately distinguishes between pure substances and mixtures based on the fixed composition of pure substances and the variable composition of mixtures. Choice B is incorrect because mixtures, not pure substances, have variable compositions. Choice C is incorrect as both pure substances and mixtures can exist in different states. Choice D is incorrect because pure substances can be compounds as well, not exclusively elements, and mixtures can contain elements and compounds.

3. In the cardiovascular system, what does the term 'double circulation' refer to?

A. The separation of oxygenated and deoxygenated blood flow within the heart.
B. The regulation of blood pressure through vasoconstriction and vasodilation.
C. The cyclic contraction and relaxation of the heart muscle.
D. The existence of two separate circulatory pathways, one for the lungs and one for the body.

Correct answer: D

Rationale: The term 'double circulation' in the cardiovascular system refers to the existence of two separate circulatory pathways, one for the lungs (pulmonary circulation) and one for the body (systemic circulation). Oxygen-poor blood is pumped from the heart to the lungs for oxygenation, and then oxygen-rich blood is pumped from the lungs back to the heart to be circulated to the rest of the body. Choices A, B, and C are incorrect as they do not accurately describe the concept of 'double circulation.' Choice A refers to the separation of oxygenated and deoxygenated blood within the heart, choice B relates to blood pressure regulation mechanisms, and choice C describes the cardiac muscle's contraction and relaxation, none of which define 'double circulation' in the context of the cardiovascular system.

4. Which hormone, produced by the pituitary gland, stimulates the production of milk in mammary glands during breastfeeding?

A. Growth hormone (GH)
B. Thyroid-stimulating hormone (TSH)
C. Prolactin
D. Follicle-stimulating hormone (FSH)

Correct answer: C

Rationale: Prolactin is the hormone produced by the pituitary gland that stimulates the production of milk in mammary glands during breastfeeding. It plays a crucial role in lactation by promoting the development of mammary tissue and the production of milk. Growth hormone (GH), thyroid-stimulating hormone (TSH), and follicle-stimulating hormone (FSH) do not directly stimulate milk production in mammary glands. Therefore, choices A, B, and D are incorrect in the context of stimulating milk production during breastfeeding.

5. What property of matter explains why ice floats on water?

A. Viscosity
B. Density
C. Buoyancy
D. Surface tension

Correct answer: C

Rationale: The correct answer is C, buoyancy. Ice floats on water due to buoyancy, a property of matter. When water freezes into ice, it becomes less dense than liquid water, causing it to float. This phenomenon occurs because the molecules in ice are more spread out compared to liquid water, resulting in ice being less dense and able to float on the surface. Choice A, viscosity, is incorrect because viscosity refers to a fluid's resistance to flow, not its ability to float. Choice B, density, is incorrect because while ice being less dense than water is the reason it floats, this choice does not explain the specific property that causes this phenomenon. Choice D, surface tension, is incorrect as it pertains to the cohesive forces between molecules at the surface of a liquid, not the reason why ice floats on water.