Actual Chemistry Practice Test HESI A2 Exam

Actual Chemistry Practice Test HESI A2 Exam 1. Using the Lewis-dot structure model, how many dots would carbon have? a) 6 b) 8 c) 2 d) 4 The correct answer is: 4 Explanation: The number of dots in a Lewis-dot structure model corresponds to the number of valance electrons for that atom. Because carbon has four valance electrons, its Lewis-dot structure model would have 4 dots. 2. Which of these would produce hydrogen ions in an aqueous solution and would turn a litmus test from blue to red? a) Lye b) Ammonia c) Vinegar d) Detergent The correct answer is: Vinegar Explanation: Blue litmus paper turns red in the presence of an acid. Ammonia, lye, and detergent are basic, so they would not give off hydrogen ions in an aqueous solution and when added to blue litmus paper the paper would remain blue. 3. Dihydrogen monoxide is better known as ____. a) Iodine b) Table salt c) Water d) Hydrogen peroxide The correct answer is: Water Explanation: Dihydrogen monoxide, or H2O, is more commonly known as water. 4. What is the most abundant element in the Earth’s crust? a) Nitrogen b) Oxygen c) Carbon d) Hydrogen The correct answer is: Oxygen Explanation: Oxygen makes up about 47% of the Earth’s crust, followed by silicon at 28%, aluminum at 8%, iron at 5%, calcium at 4%, and sodium and potassium, each at 3%. 5. What is the most abundant element in the universe? a) Hydrogen b) Helium c) Nitrogen d) Oxygen The correct answer is: Hydrogen Explanation: Hydrogen is the most abundant element in the universe, followed by helium and then oxygen.