HESI A2 Exam Chemistry Questions and Answers Latest 2022 - 2023
- Which of the following elements is not involved in many hydrogen bonds?
- fluorine
- carbon
- oxygen
- nitrogen
Explanation: Carbon is not involved in many hydrogen bonds. A hydrogen bond occurs when an atom of hydrogen that has a covalent bond with an electronegative atom forms a bond with a third atom. The original covalent bond involving hydrogen gives away protons, and the third element receives them. One of the reasons that fluorine, oxygen, and nitrogen are frequently part of a hydrogen bond is that they have a strong electronegativity and are therefore able to form more durable bonds. Chlorine is another element frequently involved in hydrogen bonds.
- What is the mass (in grams) of 0.350 mol copper?
- 12.5 g
- 14.6 g
- 18.5 g
- 22.2 g
Explanation: The mass of 0.350 mol copper is 22.2 grams. This problem requires the use of the periodic table. There you will see that the molecular mass of copper is approximately 63.5. Take this figure and multiply it by the amount of copper given by the question: 0.350 mol. The 1 / 2
resulting figure is 22.225, which, rounded to the nearest tenth, is 22.2 grams. In order to succeed on the HESI exam, you will need to be able to perform these simple calculations of mass.
- How many d orbitals are there in a d subshell?
- 5
- 7
- 9
- 11
Explanation: There are five d orbitals in a d subshell (or sublevel). Each of these orbitals can hold two electrons, so sublevel d is capable of holding 10 electrons. The s subshell has one orbital, the p subshell has three orbitals, the d subshell has five orbitals, and the f subshell has seven orbitals. In chemistry, the electron configuration of an atom is expressed in the following form, using helium as an example: 1s2. In this notation, the 1 indicates that the electrons are found in the first energy level of the atom, the s indicates that the electrons are in a spherical orbit, and the superscript 2 indicates that there are 2 total electrons in the first energy level subshell.
- What is the name for the number of protons in an atom?
- atomic identity
- atomic mass
- atomic weight
- atomic number
Explanation: The number of protons in an atom is the atomic number. Protons are the fundamental positive unit of an atom. They are located in the nucleus. In a neutral atom (an atom
- / 2