Biology - Section 1.1 Chemical Fundamentals Quiz

A proton is a subatomic particle that carries a positive charge. It is located in the nucleus of an atom along with neutrons.

The particle of an atom that carries a negative charge is the electron.

The time for half of the atoms in a sample to decay is called the half-life.

Radioisotopes spontaneously decay.

The particle of an atom that carries a neutral charge is the neutron.

Atoms of the same element with different mass numbers are called isotopes.

The correct answer is "Van der Waals forces." Van der Waals forces refer to the collective name for intermolecular bonding, which includes London dispersion, dipole-dipole interactions, and hydrogen bonding. These forces are responsible for the attractions between molecules and determine many of their physical properties.

Tracers are a useful application of unstable atoms. Tracers are substances that are used to track the movement or progress of a process. Unstable atoms, or radioisotopes, can be used as tracers because their radioactive decay can be easily detected and measured. This allows scientists to monitor the movement of these atoms in various systems, such as in medical imaging or environmental studies.

The only force of attraction between noble gases is London dispersion.

A hydrogen bond is a type of dipole-dipole force that occurs between a hydrogen atom bonded to a highly electronegative atom (such as N, O, or F) and another electronegative atom. This bond is stronger than other dipole-dipole forces because of the large electronegativity difference between hydrogen and the other atom. Therefore, the correct answer is 6.

The term "intermolecular" refers to the bonds between molecules.

In a covalent bond, two atoms share a pair of electrons. Each atom contributes one electron to the bond, resulting in a total of two electrons involved in the bond. Therefore, the correct answer is 2.

A polar molecule is one in which there is an uneven distribution of electrical charge. This means that one end of the molecule has a slight positive charge, while the other end has a slight negative charge. This occurs when the electrons in the molecule are not evenly shared between the atoms, resulting in an asymmetrical distribution of charge. The other options, such as containing double or triple bonds, being formed at extremely low temperatures, containing ions, or containing the element oxygen, do not necessarily indicate a polar molecule.

Hydrogen bonds are responsible for the surface tension properties of water because they create a cohesive force between water molecules, causing them to stick together. They are also responsible for the relatively high boiling point of water because the hydrogen bonds need to be broken in order for the water molecules to change from a liquid to a gas state. Lastly, hydrogen bonds are weaker than covalent bonds because they involve the attraction between a hydrogen atom and an electronegative atom, such as oxygen or nitrogen, rather than a sharing of electrons between atoms.

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Isomers are molecules that have the same molecular formula, meaning they have the same number and types of atoms. However, they differ in their arrangement of atoms, resulting in different structural or spatial arrangements. This can lead to differences in their physical and chemical properties. Therefore, isomers have the same molecular formula but different structures.

Buffers in living organisms help maintain the pH within a narrow range, which is crucial for the proper functioning of enzymes. Enzymes are highly sensitive to changes in pH, and even slight deviations from their optimal pH can disrupt their structure and function. By regulating the pH, buffers ensure that enzymes can maintain their active conformation and catalyze biochemical reactions efficiently. This is essential for various cellular processes and overall organismal homeostasis.

Water is a highly polar molecule because it has polar covalent bonds and an asymmetrical structure. The oxygen atom in water is more electronegative than the hydrogen atoms, causing the oxygen to have a partial negative charge and the hydrogen atoms to have partial positive charges. This uneven distribution of charge creates a dipole moment, making water a polar molecule.

A property of nonpolar molecules is that they are hydrophobic, meaning they do not dissolve in water.

The correct answer is a covalent bond. A covalent bond is formed when two atoms share electrons. In the case of a C-H bond, carbon and hydrogen share electrons to form a stable molecule. This type of bond is common in organic compounds and is characterized by the equal sharing of electrons between the carbon and hydrogen atoms. It is not an ionic bond because there is no transfer of electrons, and it is not a hydrogen bond because hydrogen bonds occur between a hydrogen atom and an electronegative atom such as oxygen or nitrogen.

The force responsible for holding polar molecules to one another is dipole-dipole interactions. This occurs when the positive end of one polar molecule attracts the negative end of another polar molecule, creating a bond between them. This force is stronger than the London dispersion forces, which are present in all molecules, and weaker than hydrogen bonding, which occurs when a hydrogen atom is bonded to a highly electronegative atom like oxygen or nitrogen.

When atoms from two different elements have similar electronegativities, it means that they have similar abilities to attract electrons. In this case, they are likely to form a nonpolar covalent bond. In a nonpolar covalent bond, the electrons are shared equally between the atoms, resulting in a balanced distribution of charge. This type of bond occurs when the electronegativity difference between the atoms is very small or nonexistent.

The answer is correct because it accurately describes the characteristics of an atom of nitrogen. The atomic mass of nitrogen is 14 atomic mass units, which is the sum of its protons and neutrons. Additionally, nitrogen has 7 electrons, which is equal to its number of protons. Therefore, the answer correctly states that nitrogen has an atomic mass of 14 atomic mass units and 7 electrons.

The pH of a solution is a measure of the concentration of hydrogen ions (H+) in the solution. A decrease in pH indicates an increase in the concentration of H+ ions, while an increase in pH indicates a decrease in the concentration of H+ ions. In this case, the pH is changing from 4.5 to 6.5, which means it is increasing by 2 units. Since pH is a logarithmic scale, a change of 2 units represents a 100-fold decrease in the concentration of H+ ions. Therefore, the concentration of H+ ions would be decreased by a factor of 100.

Element 'X' has a lower electronegativity than element 'Y'

Both elements will tend to give up an electron to become chemically stable

Both elements will form covalent bonds more readily than ionic bonds

It is highly probable that these elements will form polar covalent molecules

There is not enough information to answer this question

The pH of the resulting solution (solution 'Z') increased from 4 to 5, indicating that it became less acidic. This suggests that solution 'Y' was a base and neutralized some of the hydronium ions (H+) present in solution 'X'. Therefore, statement 2 is correct, as there were fewer hydronium ions in solution 'Z' compared to solution 'X'. Additionally, statement 4 is correct because the buffering action of solution 'X' was used up by the base in solution 'Y', resulting in the increase in pH.