The MDCAT is the Medical College Admission Test, and it’s used to determine whether or not an applicant will be accepted into medical college and how much they’ll be able to pay attention to studies. The MDCAT tests your knowledge of many different sciences, including chemistry, which requires an excellent foundation in fundamental concepts as well as advanced topics such as organic and biochemistry. These PMC MCQs on fundamental concepts of chemistry will help you get familiar with the most important building blocks of chemical processes and reactions before you take your MCAT. These MCQs will cover the following subtopics in the fundamental chemistry.

Atomic mass

An atomic mass is the sum of all the protons and neutrons in an atom’s nucleus. The number of neutrons can vary in any given atom, but the number of protons is always the same. As a result, different isotopes have different atomic masses. For example, carbon-12 has six protons and six neutrons for an atomic mass of 12; carbon-14 has six protons and eight neutrons for an atomic mass of 14.

Empirical formula

The empirical formula for water is H2O. Empirical formulas are the simplest form of chemical formulas and represent the simplest ratio of atoms in a compound. They can also be used to identify compounds that have the same proportions of elements, but different structures. For example, C6H12O6 is an empirical formula because it represents six carbon molecules and twelve hydrogen molecules, but this structure does not exist naturally in sugarcane or cane sugar.

Molecular formula

Every molecule has a molecular formula, which is the simplest way to represent it’s structure. In this case, the molecular formula for glucose is C6H12O6. This tells you that there are six molecules of carbon, twelve molecules of hydrogen and six molecules of oxygen in each glucose molecule.

Concept of mole

A mole is defined as the number of molecules in one mole of material. It is calculated by dividing the atomic or molecular weight of any substance by its molar mass. For example, 1 mole of carbon would be 12 grams because the atomic weight of carbon is 12 and its molar mass is 12 grams per molecule.

Avogadro’s number

Avogadro’s number, also called the Avogadro constant, is the number of atoms or molecules that are in 1mol. It was first measured by Amadeo Avogadro in 1811 by counting the volume and mass of equal volumes of gas over water at various temperatures. This measurement gave him the number 6.022×1023 which was rounded to 6.022×1023 for simplicity.

Stoichiometry

How many moles of H2O are created from the following reaction? 

3H2(g) + O2 (g) → 2H2O(l) 

There are two ways to answer this question. One way is to calculate the number of moles of H2 that react in order to find the number of moles of H2O. The other way is to calculate the number of moles of O2 that react, and then convert this into moles of water. Either way, there will be 2 moles of H2O formed per mole of hydrogen gas reacted. In addition, for every mole of oxygen gas reacted, one mole of H2O will form. Hence, three moles of oxygen must react with three moles of hydrogen for six total moles of H2O to form: 3*3 = 6. 

Limiting reactant

A limiting reactant is the reactant in a chemical reaction that is used up first, causing the reaction to slow down or stop. It’s important to note that this is different from an excess reactant, which is one that continues to provide reactants even when there are no more available.

Percentage yield

Calculating the percentage yield is essential in determining the efficiency of chemical reactions. To calculate this, you simply take the mass of reactants used and divide it by the mass of products created. Multiply that number by 100 and voila! You’ve got your percentage yield.

MCQs On Fundamental Concepts Of Chemistry

These MCQs are prepared from the PMC Chemistry chapter of Fundamental Concepts Of Chemistry.

Chapter: Fundamental Concepts Of Chemistry

Total MCQs: 76