HESI A2
HESI A2 Chemistry Questions
1. What is the name of the group of elements that contains chlorine, fluorine, and iodine?
- A. Alkali metals
- B. Halogens
- C. Transition metals
- D. Noble gases
Correct answer: B
Rationale: The correct answer is 'Halogens.' Halogens are a group of elements that include chlorine, fluorine, and iodine. These elements are part of Group 17 in the periodic table. They share similar properties such as high reactivity and the ability to readily form compounds. Choice A, 'Alkali metals,' is incorrect as alkali metals are found in Group 1 of the periodic table, which includes elements like lithium and sodium. Choice C, 'Transition metals,' is incorrect as transition metals are located in the middle section of the periodic table, not in Group 17. Choice D, 'Noble gases,' is incorrect as noble gases are in Group 18 and include elements like helium and neon, which are chemically inert.
2. What are the products of the combustion of a hydrocarbon?
- A. Water and carbon dioxide
- B. Water and oxygen
- C. Hydrogen and carbon monoxide
- D. Carbon dioxide and oxygen
Correct answer: A
Rationale: When a hydrocarbon undergoes combustion, it reacts with oxygen to produce water and carbon dioxide as the main products. The general chemical equation for the combustion of a hydrocarbon is hydrocarbon + oxygen → carbon dioxide + water. Therefore, the correct answer is 'Water and carbon dioxide.' Choices B, C, and D are incorrect because water and carbon dioxide are the primary products of hydrocarbon combustion, not water and oxygen, hydrogen and carbon monoxide, or carbon dioxide and oxygen.
3. Which of these elements has the greatest atomic mass?
- A. Au
- B. Ba
- C. I
- D. W
Correct answer: D
Rationale: Among the elements listed, Tungsten (W) has the greatest atomic mass. The atomic mass of Tungsten is approximately 183.84 atomic mass units (amu), while the atomic masses of the other elements listed are as follows: Gold (Au) is around 196.97 amu, Barium (Ba) is approximately 137.33 amu, and Iodine (I) is about 126.90 amu. Therefore, Tungsten (W) has the greatest atomic mass out of the given elements. Gold (Au) has a higher atomic mass than Barium (Ba) and Iodine (I), making choices A, B, and C incorrect.
4. How much concentrated HCl should be used to prepare 500 mL of a 0.100 M HCl solution?
- A. 75 mL
- B. 100 mL
- C. 125 mL
- D. 150 mL
Correct answer: B
Rationale: To prepare a 0.100 M HCl solution with a volume of 500 mL, you can use the formula C1V1 = C2V2, where C1 is the concentration of the concentrated HCl solution, V1 is the volume of concentrated HCl solution used, C2 is the desired concentration (0.100 M), and V2 is the final volume (500 mL). Rearranging the formula to solve for V1, you get V1 = (C2V2) / C1. Plugging in the values (0.100 M)(500 mL) / C1 = 100 mL, which means 100 mL of concentrated HCl should be used to prepare 500 mL of a 0.100 M HCl solution. Therefore, the correct answer is 100 mL. Choice A (75 mL), Choice C (125 mL), and Choice D (150 mL) are incorrect as they do not match the calculated volume needed to prepare the desired concentration of HCl solution.
5. In the periodic table, which group contains the alkali metals?
- A. Group 7
- B. Group 1
- C. Group 2
- D. Group 3
Correct answer: B
Rationale: The correct answer is Group 1. Alkali metals are found in Group 1 of the periodic table, which includes elements such as lithium, sodium, and potassium. These elements are known for their high reactivity and tendency to form alkaline solutions when they react with water. Therefore, Group 1 is specifically designated as the group containing alkali metals. Choice A (Group 7) is incorrect as Group 7 contains the halogens. Choice C (Group 2) is incorrect as Group 2 contains the alkaline earth metals. Choice D (Group 3) is incorrect as Group 3 contains the scandium group of elements.
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