1. Sunscreen protects the skin from harmful ultraviolet (UV) rays by

A. Reflecting UV rays away from the skin
B. Absorbing UV rays and converting them to heat
C. Blocking UV rays completely
D. Stimulating melanin production

Correct answer: B

Rationale: The correct answer is B: Absorbing UV rays and converting them to heat. Sunscreen contains ingredients that act as filters to absorb UV radiation before it reaches the skin. These filters then convert the UV rays into a less harmful form of energy, usually heat, which is then released from the body. This process helps prevent UV radiation from damaging the skin cells and causing sunburn or long-term skin damage. Reflecting UV rays away from the skin (A) and blocking UV rays completely (C) are not accurate functions of sunscreen. Additionally, stimulating melanin production (D) is not a direct way in which sunscreen protects the skin from UV rays.

2. Which type of reaction is represented by the equation A + B â†’ AB?

A. Synthesis
B. Decomposition
C. Single Replacement
D. Double Replacement

Correct answer: a

Rationale: Synthesis reactions involve the combination of two or more substances to form a new compound.

3. The theory of evolution by natural selection suggests that:

A. Organisms evolve towards perfection
B. Traits are acquired through use and disuse
C. Individuals with favorable traits survive and reproduce more
D. All of the above

Correct answer: C

Rationale: Rationale: A) Organisms evolve towards perfection - This statement is incorrect. Evolution by natural selection does not suggest that organisms evolve towards perfection. Instead, it emphasizes the adaptation of organisms to their environment over time. B) Traits are acquired through use and disuse - This statement reflects Lamarck's theory of evolution, not Darwin's theory of evolution by natural selection. Lamarck proposed that organisms could acquire traits during their lifetime and pass them on to their offspring, which has been largely discredited. C) Individuals with favorable traits survive and reproduce more - This statement accurately reflects the central concept of Darwin's theory of evolution by natural selection. Individuals with traits that are advantageous in their environment are more likely to survive and reproduce, passing on those traits to future generations. D) All of the above - This option is incorrect because not all of the statements are true. Only option C a

4. You need to fill a rectangular swimming pool with dimensions 10 meters by 5 meters and a depth of 2 meters. How many cubic meters of water does it take to fill the pool?

A. 50 cu m
B. 100 cu m
C. 150 cu m
D. 200 cu m

Correct answer: C

Rationale: Simply multiply the pool's dimensions to find its volume.

5. What principle explains the relationship between pressure, volume, and temperature for ideal gases?

A. Law of conservation of energy
B. Newton's laws of motion
C. Ideal gas law
D. Archimedes' principle

Correct answer: C

Rationale: The ideal gas law (PV = nRT) relates pressure, volume, and temperature for ideal gases at constant number of moles and temperature.

6. What is the main function of the epiglottis?

A. To store bile
B. To absorb nutrients
C. To prevent food from entering the trachea
D. To produce digestive enzymes

Correct answer: C

Rationale: Rationale: The epiglottis is a flap of cartilage located at the base of the tongue that covers the opening of the trachea during swallowing to prevent food and liquids from entering the airway. This action helps direct food and liquids into the esophagus, which leads to the stomach for digestion, while also protecting the respiratory system from potential blockages that could lead to choking or aspiration pneumonia. Options A, B, and D are incorrect as the epiglottis is not involved in storing bile, absorbing nutrients, or producing digestive enzymes.