1. Which part of a plant cell is responsible for photosynthesis?
Solution
Correct: B
Chloroplasts contain chlorophyll, the green pigment that captures light energy and uses it to make glucose during photosynthesis.
2. A student measures the mass of a rock as 250 g and its volume as 100 cm³. What is the density of the rock?
Solution
Correct: B
Density = mass ÷ volume = 250 g ÷ 100 cm³ = 2.5 g/cm³.
3. Which of the following is an example of a chemical change?
Solution
Correct: C
Burning wood produces new substances such as carbon dioxide and ash, making it a chemical change.
4. What is the main function of the red blood cells in the human body?
Solution
Correct: B
Red blood cells contain hemoglobin, which binds to oxygen in the lungs and transports it to body tissues.
5. Which simple machine is found in the head of an axe?
Solution
Correct: C
An axe head is a wedge, a sloped surface that splits material apart when force is applied.
6. Water freezes at 0 °C. What is this temperature on the Kelvin scale?
Solution
Correct: C
To convert Celsius to Kelvin, add 273: 0 °C + 273 = 273 K.
7. Which type of rock is formed when magma cools and solidifies?
Solution
Correct: C
Igneous rocks such as granite form directly from the cooling and crystallization of magma or lava.
8. A food web shows arrows pointing from a mouse to a snake. What do the arrows represent?
Solution
Correct: A
Arrows in a food web show the direction of energy transfer, here from the mouse (prey) to the snake (predator).
9. Which force causes a book to slow down when sliding across a table?
Solution
Correct: C
Friction opposes the motion between the book and the table, converting kinetic energy into heat and slowing the book.
10. What is the name of the process by which a liquid changes into a gas at the surface?
Solution
Correct: B
Evaporation occurs when particles at the surface of a liquid gain enough energy to escape into the gas phase.
11. Which planet in our solar system has the shortest day, completing one rotation in about 10 hours?
Solution
Correct: C
Jupiter rotates very rapidly; its day lasts only about 9.9 Earth hours.
12. An electromagnet is created by wrapping wire around an iron nail and connecting the wire to a battery. What happens if you remove the iron nail?
Solution
Correct: B
The iron core greatly increases the magnetic field; without it, the magnetic field is too weak to act as an electromagnet.
13. Which of these substances is an example of an element?
Solution
Correct: C
Gold (Au) is made of only one type of atom, so it is an element, whereas the others are compounds.
14. A student shines a flashlight at a mirror. Which statement best describes the light after it hits the mirror?
Solution
Correct: C
According to the law of reflection, the angle of incidence equals the angle of reflection.
15. Which human body system is primarily responsible for transporting nutrients, oxygen, and wastes?
Solution
Correct: B
The circulatory system (heart, blood, blood vessels) moves nutrients, oxygen, and wastes to and from cells.
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