Chem 1A Quiz 3 Practice Test

An atom is the basic unit of an element that retains its chemical properties. Molecules and compounds are made up of atoms and therefore do not represent the smallest unit of matter.

Protons have a positive charge, while neutrons have no charge and electrons have a negative charge. Photons are energy particles and do not carry a charge in this context.

The nucleus is the central core of the atom where protons and neutrons are located. The electron cloud surrounds the nucleus and contains electrons.

Electron configuration refers to the arrangement of electrons within an atom's orbitals. The other terms refer to different atomic properties and do not describe electron distribution.

An element is a substance that consists entirely of one type of atom, whereas compounds, mixtures, and alloys include two or more different types of atoms. This makes an element the simplest form of pure substance.

The law of conservation of mass asserts that mass is conserved throughout chemical reactions, meaning the mass of the reactants equals the mass of the products. The other laws describe different chemical properties and relationships.

Increasing the temperature escalates the kinetic energy of molecules, resulting in more frequent and energetic collisions. This increase in collision frequency and energy generally leads to an increased reaction rate.

Covalent bonds result from the sharing of electron pairs between atoms, establishing a stable balance between attractive and repulsive forces. In contrast, ionic bonds involve electron transfer, and metallic as well as hydrogen bonds have different bonding characteristics.

Electronegativity quantifies the ability of an atom to attract electrons when it forms a chemical bond. The other options refer to ionization energy, atomic size, and reaction kinetics, which are distinct concepts.

Boyle's Law states that the pressure of a gas is inversely proportional to its volume when temperature is held constant. The other gas laws address relationships involving temperature, volume, moles, or partial pressures.

A catalyst provides an alternative pathway with a reduced activation energy, thereby accelerating the reaction without undergoing any permanent chemical change itself. It does not alter the overall energy level or temperature of the reaction.

A balanced chemical equation maintains the same number of atoms for each element on both sides in accordance with the law of conservation of mass. It does not necessarily indicate anything about the excess of reactants or the preferential formation of products.

A low pH value signifies a high concentration of hydrogen ions, which is typical of acidic solutions. High pH values correspond to basic conditions, and neutral pH reflects a balance in ion concentration.

The rate of a chemical reaction is influenced by temperature, concentration, and catalysts, which affect collision frequency and energy. The color of reactants has no impact on the reaction rate.

Molarity is defined as the number of moles of a solute per liter of solution. The other options either use different units or refer to other concentration measurements.

The reaction requires 2 moles of H2 for every 1 mole of O2, so 4 moles of H2 and 2 moles of O2 are exactly in the stoichiometric ratio. This means both reactants will be completely consumed during the reaction.

In an endothermic reaction, heat acts as a reactant; therefore, increasing the temperature shifts the equilibrium towards the products and raises the equilibrium constant. This response aligns with Le Chatelier's principle.

Activation energy is the minimum energy barrier that reacting particles must overcome for a successful collision leading to a reaction. The other terms refer to different energy concepts not directly related to the collision process.

The oxidizing agent gains electrons during a redox reaction, which causes another species to be oxidized. This acceptance of electrons is the defining characteristic of an oxidizing agent.

A decrease in volume increases the pressure of the system, prompting the equilibrium to shift toward the side with fewer moles of gas. In this reaction, the right side (NH3) has fewer moles of gas, so the equilibrium shifts to the right.