Nokea
What term describes the bouncing back of waves after striking a surface or boundary?
- A. Diffraction
- B. Refraction
- C. Reflection
- D. Interference
Correct Answer: C
Rationale: The correct answer is 'Reflection.' Reflection is the term used to describe the bouncing back of waves after striking a surface or boundary. Diffraction, on the other hand, refers to the bending of waves around obstacles. Refraction is the bending of waves as they pass from one medium to another. Interference involves the combination of two or more waves that results in a new wave pattern. Therefore, in this context, choices A, B, and D are incorrect as they do not specifically relate to the bouncing back of waves after striking a surface or boundary.
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Which of the following is an example of an unsaturated fatty acid?
- A. Stearic acid
- B. Palmitic acid
- C. Oleic acid
- D. Butyric acid
Correct Answer: C
Rationale: Oleic acid is an example of an unsaturated fatty acid because it contains one or more double bonds in its hydrocarbon chain, leading to kinks in the chain structure. This unsaturation gives it a lower melting point compared to saturated fatty acids. Stearic acid (A), Palmitic acid (B), and Butyric acid (D) are examples of saturated fatty acids as they do not contain any double bonds in their hydrocarbon chains, leading to a straight structure and higher melting points.
A rocket blasts off from Earth. What is the main force propelling the rocket upwards?
- A. Gravitational force
- B. Air resistance
- C. Thrust from the rocket engine
- D. Normal force from the launchpad
Correct Answer: C
Rationale: The main force propelling the rocket upwards is the thrust from the rocket engine. Thrust is the force produced by the rocket engine pushing exhaust gases in the opposite direction, following Newton's third law of motion (action and reaction). This thrust overcomes the force of gravity and allows the rocket to lift off and move upwards. Choice A, gravitational force, is incorrect as gravity pulls objects towards the Earth, and in this case, the rocket is moving against gravity. Choice B, air resistance, is incorrect because it opposes the motion of the rocket and is more relevant during descent rather than ascent. Choice D, normal force from the launchpad, is incorrect as this force acts perpendicular to the surface and does not propel the rocket upwards.
What is the stoichiometric coefficient of nitrogen (N2) in the balanced equation for the Haber process: N2 + 3H2 → 2NH3?
- A. 1
- B. 2
- C. 3
- D. 4
Correct Answer: A
Rationale: In the balanced equation for the Haber process: N2 + 3H2 → 2NH3, the stoichiometric coefficient of nitrogen (N2) is 1. This means that one molecule of nitrogen reacts with three molecules of hydrogen to produce two molecules of ammonia. The coefficient '1' indicates the mole ratio of N2 in the reaction. Choice B, 2, is incorrect because it represents the coefficient for ammonia (NH3) in the balanced equation. Choice C, 3, is incorrect as it corresponds to the coefficient of hydrogen (H2). Choice D, 4, is not the correct stoichiometric coefficient for nitrogen (N2) in this equation.
How does the human eye focus light?
- A. Cornea
- B. Iris
- C. Lens
- D. Retina
Correct Answer: C
Rationale: The human eye focuses light by adjusting the shape of its lens. The lens changes shape to allow the eye to focus on objects at different distances, a process known as accommodation. The cornea is the transparent outer covering of the eye that helps to focus light but does not change shape like the lens. The iris controls the size of the pupil to regulate the amount of light entering the eye. The retina is the light-sensitive layer at the back of the eye that receives and processes images but does not adjust the focus of light.
The adrenal cortex produces a group of steroid hormones called corticosteroids. What is a MAJOR function of corticosteroids?
- A. Regulate insulin sensitivity and blood sugar levels
- B. Control blood pressure and electrolyte balance
- C. Stimulate the immune system and inflammatory response
- D. Promote growth and development during puberty
Correct Answer: B
Rationale: Corticosteroids, produced by the adrenal cortex, primarily function to control blood pressure and electrolyte balance. One of the key corticosteroids, aldosterone, plays a crucial role in regulating sodium and potassium levels in the body. This regulation is essential for maintaining blood pressure and electrolyte balance. Choices A, C, and D are incorrect because corticosteroids do not primarily regulate insulin sensitivity and blood sugar levels, stimulate the immune system and inflammatory response, or promote growth and development during puberty. While corticosteroids can have effects on insulin sensitivity, immune response, and growth, their major role is in maintaining blood pressure and electrolyte balance.