1.
Which of the following statements is false?
Correct Answer
B. Water heats up and cools down very quickly.
Explanation
Compared to other liquids, water absorbs more heat before it becomes measurably hotter, since the water temperature is stable. This is due to the extensive hydrogen bonding that restricts the jiggling of water molecules.
2.
Your friend Jonathan has a test in 2 minutes and he runs towards you to ask you this question: What do isotopes of the same element have in common?
What do you answer him to be correct?
Correct Answer
A. They have the same number of protons.
Explanation
Isotopes of the same element have the same number of protons. This is because isotopes are atoms of the same element that have different numbers of neutrons, but the same number of protons. The number of protons determines the element's identity, so isotopes of the same element will always have the same number of protons. The number of neutrons may vary, which results in different mass numbers for different isotopes.
3.
Atoms are tiny particles, the _________ _________ of all substances.
Correct Answer
building blocks
Explanation
Atoms are the fundamental units or "building blocks" of all substances. They are the smallest particles that make up matter and cannot be broken down into smaller components without losing their chemical properties. Atoms combine together to form molecules and compounds, which then make up the various substances we encounter in our daily lives. Therefore, the correct answer is "building blocks."
4.
Your friend Maria tells you that the teacher did not correct her test properly. She claims to have a right answer. Is the statement below true or did the teacher really make a mistake?
Statement: An element is a pure substance. Each kind consists only of atoms with different number of protons.
Correct Answer
B. It is False, Maria did get the question wrong.
Explanation
An element is a pure substance. Each kind consists only of atoms with the same number of protons. Maria is wrong.
5.
What are compounds?
Correct Answer
D. They are molecules that consist of two or more different elements in proportions that do not vary. They do bond together.
Explanation
Water is an example. All water molecules have one oxygen and two hydrogen atoms. In a sea or lake, an ocean or a pool, its molecules have twice as many hydrogen as oxygen atoms.
6.
Electronegativity is a measure of an atom's ability to pull electrons from other atoms. It is a measure of charge.
Correct Answer
B. False
Explanation
Electronegativity is a measure of an atom's ability to pull electrons from other atoms. Whether the pull is strong or weak depends on the atom's size and how many vacancies it has; it is not a measure of charge. Example: A chlorine atom uncharged, it has 17 protons and 17 electrons. On its valence electron's shell, it has 7 electrons. (which can hold eight) It has one vacancy. An uncharged chlorine atom is highly electronegative--- it can pull an electron away from another atom and fill its third shell.It would then become a chlorine ion. ( Cl-)
7.
What are some properties of a mixture?
Correct Answer(s)
A. 2 or more substances intermingle
D. The substances do not form chemical bonds.
E. Their proportions can vary.
Explanation
A mixture is a combination of two or more substances that intermingle without forming chemical bonds. This means that the substances retain their individual properties and can be separated physically. Additionally, in a mixture, the proportions of the substances can vary, meaning that different amounts of each substance can be present in the mixture.
8.
A chemical bond is an ________ _____ that arises between two atoms when their electrons interact.
Correct Answer(s)
attractive force
Explanation
A chemical bond is an attractive force that arises between two atoms when their electrons interact. This force pulls the atoms together and forms a bond between them. The electrons of one atom are attracted to the positively charged nucleus of the other atom, creating a stable arrangement. This attraction allows the atoms to share, transfer, or redistribute their electrons, leading to the formation of various types of chemical bonds such as covalent, ionic, or metallic bonds. Overall, the attractive force between the electrons of two atoms plays a crucial role in holding molecules and compounds together.
9.
A molecule is formed when two or more atoms of the same different elements join in chemical bonds.
Correct Answer
A. True
Explanation
Atoms with vacancies can form chemical bonds. Chemical bonds connect atoms into molecules.
10.
Which type of bonding usually forms stronger bonds?
Correct Answer
A. Covalent bonds.
Explanation
Covalent bonds tend to be stronger than ionic bonds, but they are not always so.
11.
Ionic bonds usually form by the direct transfer of an electron from one atom to another.
Correct Answer
B. False
Explanation
Ionic bond, which is a strong mutual attraction of two oppositely charged ion, does not usually form by the direct transfer of an electron from one atom to another; rather, atoms that have already become ions stay close together because of their opposite charges. E.g: NaCl; in such solids, ionic bonds hold sodium and chloride ions in an orderly, cubic arrangement.
12.
During a biology lecture, the teacher notices that students are half listening and decides to give a surprise quiz with one question. She writes "Some covalent bonds are nonpolar. What does this mean? " Which of these answers is correct?
Correct Answer
B. ....the atoms participating in the bond are sharing electrons equally.
Explanation
If nonpolar, the atoms participating in the bond are sharing electrons equally. There is no difference in charge between the two ends of such bonds. Nonpolar covalent bonds form between atoms with identical electronegativity.
13.
Polar covalent bonds do not share electrons equally. Such bonds can form between atoms with small differences in electronegativity.
Correct Answer
A. True
Explanation
Polar covalent bonds occur when the electrons in a bond are not shared equally between the atoms involved. This happens when there is a difference in electronegativity, which is the ability of an atom to attract electrons towards itself. If the electronegativity difference between the atoms is small, a polar covalent bond can form. Therefore, the given statement is true.
14.
Any seperation that pulls the electron a little more towards it ''end'' of the bond so that the atom bears a slightly negative charge making the other bear a positive charge; into distinct positive and and negative regions; is called __________.
Correct Answer
polarity
Explanation
Polarity refers to the separation of charges in a molecule or bond. When there is a difference in electronegativity between atoms in a bond, the electrons are pulled towards the more electronegative atom, creating a slightly negative charge on that atom and a slightly positive charge on the other atom. This separation of charges creates distinct positive and negative regions in the molecule or bond, which is known as polarity.
15.
Evaporation helps liquid water stabilize ___________.
Correct Answer
temperature
Explanation
Evaporation heat energy converts liquid water to gas. It takes heat to convert liquid water to gas, so the surface temperature of water decreases during evaporation. ( Can cool you off when you sweat)
16.
Hydrophilic dissolve easily in water, while hydrophobic substances do not.
Correct Answer
A. True
Explanation
Hydrophilic substances have an affinity for water and can easily dissolve in it. On the other hand, hydrophobic substances repel water and do not dissolve in it. Therefore, it is true that hydrophilic substances dissolve easily in water while hydrophobic substances do not.
17.
Your little sister comes up to you with her homework. She tells you she doesn't understand her bonus question. The question is: What is the difference between solutes and solvents? Can you answer it?
Correct Answer
A. Solutes dissolve in a solvent.
Explanation
An example of a solvent is water.
18.
During a test you hear a student bursting with an insight for question #6. The student says: Cohesion breaks water molecules apart! Is the student correct?
Correct Answer
B. False
Explanation
Cohesion keeps water molecules together. It means that molecules resist seperating from one another. E.g: Water with its hydrogen bonds. The bond is so strong that the molecules stay together rather than spreading out like a thin film when you throw a pebble into a pond.
19.
Mrs. Salvador writes this on the board : pH is a measure of the number of hydrogen ions in a solution.
Is she correct?
Correct Answer
A. True
Explanation
Mrs. Salvador is correct. pH is indeed a measure of the number of hydrogen ions in a solution. It is a scale that ranges from 0 to 14, with 0 being highly acidic, 7 being neutral, and 14 being highly alkaline. The pH value indicates the acidity or alkalinity of a solution based on the concentration of hydrogen ions present. Therefore, the statement is true.
20.
For a solution to be neutral or 7 (numerical form), the number of H+ ions must be the _____ to the number of OH- ions.
Correct Answer
same
Explanation
In order for a solution to be neutral, the number of H+ ions (acidic) must be the same as the number of OH- ions (basic). This balance of acidic and basic ions results in a solution with a pH value of 7.
21.
Joe is in the new laboratory and is told to put up a personalised pH scale. If you were in his position, what range would you use for the pH scale?
Correct Answer
F. 0-14
Explanation
0-7 is acidic, 7-14 is basic. 7 is neutral.
22.
Cellia was in cell biology class when she suddenly fell asleep. The teacher noticed and called upon her. Cellia turns around and asks you the question so you can help her.
Question: What do salts release?
Correct Answer
C. None of the above.
Explanation
Salts are dissolved easily in water and release ions other than H+ or OH-. For example= NaCl --- > Na+ + Cl-.
23.
Timothy is trying to help his mom to put away her groceries and tems she bought from the pharmacy. She tells him that she puts them away by seperating the acids from bases. Timothy is given the list of solutions that were bought. Check off the basic solutions.
Correct Answer(s)
A. Oven cleaner.
F. Ammonia.
G. Blood.
I. Tums.
K. Egg white.
M. Toothpaste.
N. Bleach.
O. Hair remover.
Explanation
Basic solutions are substances that have a pH greater than 7. In the given list, the basic solutions are oven cleaner, ammonia, blood, Tums, egg white, toothpaste, bleach, and hair remover. These substances are known to have a pH greater than 7 and therefore can be classified as basic solutions.
24.
Acids release H+ and bases accept H+.
Correct Answer
A. True
Explanation
Acids are substances that release hydrogen ions (H+) when dissolved in water, while bases are substances that accept hydrogen ions. This statement is true because it accurately describes the behavior of acids and bases. Acids donate H+ ions, which increases the concentration of H+ in a solution, while bases accept H+ ions, which decreases the concentration of H+.
25.
Janie was faced with a thief when she crossed the forbidden road. The thief asked her a question about acids and bases! The only way she could escape him was by getting his question correctly. Can you help Jennie escape?
The Question: What is a buffer system?
Correct Answer
A. It keeps a solution within a consistent range of pH.
Explanation
A buffer system is a solution that helps maintain a consistent pH level. It resists changes in pH when small amounts of acid or base are added to it. This is important because many biological processes and reactions require a specific pH level to function properly. By keeping the pH within a consistent range, a buffer system ensures that these processes can occur smoothly without any drastic changes in acidity or basicity.