1.
The energy required for photosynthesis is provided by
Correct Answer
B. Sunlight
Explanation
Sunlight is the correct answer because photosynthesis is a process in which plants convert sunlight into energy. Sunlight provides the necessary energy for the synthesis of carbohydrates, which are the main source of energy for plants. Without sunlight, plants would not be able to carry out photosynthesis and produce the energy they need to survive and grow. Therefore, sunlight is crucial for the process of photosynthesis.
2.
Which of these is the independent variable in this experiment?
Correct Answer
D. Intensity of light
Explanation
The Independent variable is ALWAYS on the x-axis.
3.
The pH of pure water is _______
Correct Answer
C. 7.0
Explanation
The pH of pure water is 7.0 because it is considered neutral. The pH scale ranges from 0 to 14, with values below 7 being acidic and values above 7 being alkaline. Pure water has an equal concentration of hydrogen ions (H+) and hydroxide ions (OH-), resulting in a neutral pH of 7.0.
4.
Substances with a pH less than 7 are considered to be _________
Correct Answer
A. Acidic
Explanation
Substances with a pH less than 7 are considered to be acidic because pH is a measure of the concentration of hydrogen ions in a solution. A pH value less than 7 indicates a higher concentration of hydrogen ions, which means the solution is more acidic in nature.
5.
When water freezes, it _____________.
Correct Answer
A. Expands
Explanation
When water freezes, it expands. This is because the water molecules arrange themselves in a hexagonal lattice structure when they freeze, which takes up more space than when they are in the liquid state. As a result, the volume of water increases as it freezes, causing it to expand. This expansion is why ice floats on water, as it is less dense than the liquid water.
6.
The expansion of ice could be a cause of what condition in a living cell?
Correct Answer
C. The death of the cell because it "pops."
Explanation
When water freezes and turns into ice, it expands in volume. This expansion can cause the cell membrane to rupture or "pop," leading to the death of the cell.
7.
If you spill a chemical during an experiment, what is the first thing you should do?
Correct Answer
B. Tell the teacher
Explanation
In the event of a chemical spill during an experiment, the first thing you should do is inform the teacher. This is important because the teacher is trained and experienced in handling such situations and can provide guidance on how to safely clean up the spill. They can also take necessary precautions to ensure the safety of everyone in the room and prevent any potential hazards or accidents.
8.
Two common acids are _______ and __________.
Correct Answer
D. Lemon juice and vinegar
Explanation
Lemon juice and vinegar are both examples of common acids. They are acidic substances that contain hydrogen ions and can react with bases to form salts. Lemon juice is acidic due to the presence of citric acid, while vinegar is acidic because of acetic acid. Both lemon juice and vinegar are commonly used in cooking and can add a sour taste to dishes.
9.
If a substance was dissolved in water, what do you think would happen to water's cohesive properties?
Correct Answer
B. They would decrease
Explanation
When a substance is dissolved in water, it disrupts the hydrogen bonding between water molecules. Hydrogen bonding is responsible for the cohesive properties of water, such as surface tension and the ability to form droplets. Therefore, when a substance is dissolved in water, the cohesive properties of water would decrease.
10.
Some chemicals leaked into a pond and dissolved into the water. What would likely happen to the ability of insects like water striders to walk on water?
Correct Answer
B. It would decrease.
Explanation
Chemicals that dissolve into water can disrupt the surface tension of the water, making it more difficult for insects like water striders to walk on it. Surface tension is the property that allows insects to distribute their weight evenly and stay afloat on the water's surface. When chemicals are introduced, they can break the cohesive forces between water molecules, reducing surface tension and making it harder for water striders to walk on the water. Therefore, the ability of water striders to walk on water would likely decrease.