Nokea
What is the normal body temperature in °C?
- A. 36°C
- B. 37°C
- C. 35°C
- D. 40°C
Correct Answer: B
Rationale: The normal body temperature for humans is 37°C. This temperature is considered average and is a standard reference point for assessing an individual's health status. It is essential for the body to maintain this temperature to ensure optimal functioning of various physiological processes. Choice A (36°C) is incorrect as it is slightly below the normal body temperature. Choice C (35°C) is also incorrect as it is significantly lower than the normal body temperature. Choice D (40°C) is incorrect as it is significantly higher than the normal body temperature and would indicate a fever or other health issue.
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How many neutrons are in an atom of uranium-235?
- A. 92
- B. 125
- C. 143
- D. 235
Correct Answer: A
Rationale: The correct answer is A: '92'. To determine the number of neutrons in an atom, you subtract the atomic number (number of protons) from the atomic mass number. For uranium-235, the atomic number is 92, and the atomic mass number is 235. Subtracting 92 from 235 gives us 143 neutrons in an atom of uranium-235. Therefore, options B, C, and D are incorrect as they do not represent the correct number of neutrons in an atom of uranium-235.
What is an alloy in which another metal is dissolved in mercury (Hg) called?
- A. Electrum
- B. Amalgam
- C. Solder
- D. Bronze
Correct Answer: B
Rationale: An amalgam is a type of alloy where another metal is dissolved in mercury (Hg). This process forms a unique mixture that has various applications in dentistry, chemistry, and other fields. Electrum is a natural alloy of gold and silver, solder is a metal alloy used to join other metals together, and bronze is a copper-tin alloy. Therefore, the correct answer is B - Amalgam.
What is the number of protons in the atomic nucleus of an alkali metal?
- A. 9
- B. 10
- C. 11
- D. 12
Correct Answer: C
Rationale: The number of protons in the atomic nucleus of an alkali metal is 11. Alkali metals, belonging to group 1 of the periodic table, have 1 electron in their outer shell, which corresponds to 1 proton in their nucleus. Therefore, the correct answer is option C: 11. Choice A (9) is incorrect because it does not match the number of protons in an alkali metal. Choice B (10) is incorrect as it is also not the correct number of protons for an alkali metal. Choice D (12) is incorrect as it is not the typical number of protons found in the nucleus of an alkali metal.
How many times more acidic is a substance with a pH of 3 compared to a substance with a pH of 5?
- A. 8
- B. 2
- C. 100
- D. 1,000
Correct Answer: D
Rationale: The pH scale is logarithmic, indicating that each pH unit change reflects a 10-fold difference in acidity level. Going from pH 5 to pH 3 involves a difference of 2 units, which translates to a 100-fold increase in acidity level (10^2 = 100 for each unit). Therefore, a substance with a pH of 3 is 1,000 times more acidic than a substance with a pH of 5 (100 * 10 = 1,000). Choice A (8) is incorrect as it does not consider the logarithmic nature of the pH scale. Choice B (2) is incorrect because it represents the difference in pH units, not the increase in acidity level. Choice C (100) is incorrect as it miscalculates the increase in acidity level, which is 1,000 times and not 100 times.
On what concept is Kelvin based?
- A. Freezing point
- B. Absolute zero
- C. Boiling point
- D. Evaporation point
Correct Answer: B
Rationale: The correct answer is B: Absolute zero. Kelvin is based on the concept of absolute zero, which is the point where molecular movement ceases entirely. This temperature scale starts at absolute zero (0K), where theoretically no molecular movement occurs. Choices A, C, and D are incorrect because Kelvin is not based on the freezing point, boiling point, or evaporation point, but rather on the absolute absence of molecular motion.