1. Which hormone, produced by the thyroid gland, plays a crucial role in regulating the body's metabolism, growth, and development?

A. Calcitonin
B. Parathyroid hormone (PTH)
C. Thyroxine
D. Insulin

Correct answer: c

Rationale: The correct answer is C: Thyroxine. Thyroxine, also known as T4, is a hormone produced by the thyroid gland that plays a crucial role in regulating the body's metabolism, growth, and development. It controls how the body uses energy, affects heart rate, and influences other vital functions. Calcitonin (A) is involved in calcium regulation, not metabolism. Parathyroid hormone (PTH) (B) is produced by the parathyroid glands and regulates calcium and phosphorus levels in the body. Insulin (D) is a hormone produced by the pancreas that regulates blood sugar levels, not metabolism or growth.

2. A birdbath has a hemispherical bowl with a diameter of 30cm. What is its volume?

A. 675 cu cm
B. 1350 cu cm
C. 2700 cu cm
D. 4050 cu cm

Correct answer: C

Rationale: Use half the formula for a sphere's volume: (2/3) * Ï€ * (radius)^3. Calculate the radius (15cm) and substitute: (2/3) * Ï€ * (15cm)^3 â‰ˆ 2700 cu cm.

3. In the reaction 2H2 + O2 â†’ 2H2O, how many moles of oxygen are required to react completely with 4 moles of hydrogen?

A. 1
B. 2
C. 3
D. 4

Correct answer: 2

Rationale: The balanced equation indicates a 1:1 ratio between H2 and O2, so 4 moles of H2 require 4 moles of O2, and 2 moles of H2 require 2 moles of O2.

4. The speed of light in a vacuum is measured in units of:

A. Meters per second
B. Hertz
C. Candela
D. Newton

Correct answer: A

Rationale: The correct answer is A: 'Meters per second.' The speed of light in a vacuum is a fundamental constant of nature and is approximately 299,792,458 meters per second. This speed is constant and does not vary based on the frequency or wavelength of light. Hertz (B) is a unit of frequency, Candela (C) is a unit of luminous intensity, and Newton (D) is a unit of force. Understanding the units used to measure the speed of light is important in physics and related fields to accurately describe the propagation of light in different mediums.

5. Which of the following is a property of amphiprotic substances?

A. React with acids only
B. React with bases only
C. Can act as both acids and bases
D. Are inert in chemical reactions

Correct answer: C

Rationale: Amphiprotic substances can donate or accept a proton, so they can act as both acids and bases. The other choices do not accurately describe amphiprotic substances.

6. Cherenkov radiation is a characteristic phenomenon associated with:

A. Alpha particle emission
B. Beta particle emission
C. Gamma ray emission
D. Charged particles exceeding the speed of light in a medium

Correct answer: C

Rationale: Cherenkov radiation is a phenomenon associated with charged particles exceeding the speed of light in a medium. When a charged particle travels faster than the speed of light in that medium, it emits a characteristic blue glow known as Cherenkov radiation. This occurs due to the disruption of the electromagnetic field in the medium by the high-speed particle. Options A, B, and C are not correct as they do not directly relate to the specific condition required for Cherenkov radiation to be produced. Therefore, option D, 'Charged particles exceeding the speed of light in a medium,' is the correct answer.