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 statement accurately describes the electron cloud model of the atom?

A. Electrons precisely orbit the nucleus in defined paths.
B. Electrons occupy specific energy levels around the nucleus with varying probabilities.
C. Electrons are clustered tightly within the nucleus.
D. Electrons move randomly throughout the entire atom.

Correct answer: B

Rationale: Electrons occupy specific energy levels around the nucleus with varying probabilities. The electron cloud model depicts electrons existing in distinct energy levels, not fixed orbits, with probabilities of finding them in specific regions.

3. The science of classifying organisms into different groups based on their evolutionary relationships is called:

A. Taxonomy
B. Microbiology
C. Genetics
D. Epidemiology

Correct answer: A

Rationale: Rationale: Taxonomy is the science of classifying organisms into different groups based on their evolutionary relationships. It involves identifying, naming, and categorizing living organisms according to their similarities and differences. Microbiology (option B) is the study of microorganisms, Genetics (option C) is the study of genes and heredity, and Epidemiology (option D) is the study of the distribution and determinants of health-related states or events in populations.

4. Two cars with different masses collide head-on. Which car experiences a greater change in momentum?

A. The car with the larger mass
B. The car with the smaller mass
C. Both cars experience the same change in momentum
D. It depends on the initial velocities of the cars

Correct answer: B

Rationale: The car with the smaller mass. Although momentum is conserved in the collision, the change in momentum is inversely proportional to mass. Therefore, the car with the smaller mass will experience a larger relative change.

5. Relatively prime numbers share no common factors other than 1. Which of the following pairs of numbers are relatively prime?

A. 12 and 16
B. 15 and 17
C. 20 and 24
D. 28 and 36

Correct answer: B

Rationale: Rationale: - Relatively prime numbers are numbers that share no common factors other than 1. - To determine if two numbers are relatively prime, we need to find the greatest common divisor (GCD) of the two numbers. If the GCD is 1, then the numbers are relatively prime. - Let's calculate the GCD for each pair of numbers: A) GCD(12, 16) = 4, not relatively prime B) GCD(15, 17) = 1, relatively prime C) GCD(20, 24) = 4, not relatively prime D) GCD(28, 36) = 4, not relatively prime Therefore, the pair of numbers 15 and 17 are relatively prime because their greatest common divisor is 1, meaning they share no common factors other than 1.

6. Which property of matter explains why ice floats on water?

A. Viscosity
B. Density
C. Buoyancy
D. Surface tension

Correct answer: c

Rationale: Buoyancy is the upward force exerted by a fluid (like water) on an object immersed in it. Ice floats on water because it is less dense than water, experiencing an upward force (buoyancy) greater than its weight.