Nokea
When propane is reacted in the presence of oxygen gas, the products of this combustion reaction are:
- A. C + H2
- B. CH2 + H2O
- C. CO2 + H2
- D. CO2 + H2O
Correct Answer: D
Rationale: When propane undergoes combustion in the presence of oxygen, it forms carbon dioxide (CO2) and water (H2O). The balanced chemical equation for this reaction is: C3H8 + 5O2 -> 3CO2 + 4H2O. This means that three molecules of carbon dioxide and four molecules of water are produced when one molecule of propane reacts with five molecules of oxygen. Therefore, option D (CO2 + H2O) is the correct answer.
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What is 119 K in degrees Celsius?
- A. 32C
- B. -154C
- C. 154C
- D. -32C
Correct Answer: B
Rationale: To convert from Kelvin to Celsius, you subtract 273.15 from the temperature in Kelvin. Therefore, 119 K - 273.15 = -154C. Hence, 119 K is equivalent to -154C. The correct answer is -154C, as it results from the conversion formula from Kelvin to Celsius.
What is the SI unit of energy?
- A. ohm
- B. joule
- C. henry
- D. newton
Correct Answer: B
Rationale: The correct answer is B: joule. The joule is the SI unit of energy, defined as the work done by a force of one newton acting over a distance of one meter. It is extensively used to measure energy in various fields such as physics, chemistry, and engineering.
What is the correct name for aqueous HI?
- A. hydroiodic acid
- B. hydrogen iodide
- C. iodine hydrogen
- D. hydroiodine acid
Correct Answer: A
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What is present in an emulsion?
- A. Water and salt
- B. Two or more immiscible liquids
- C. Any liquids
- D. All of the above
Correct Answer: B
Rationale: In an emulsion, two or more immiscible liquids are present. Immiscible liquids are those that do not mix together and form separate layers, such as oil and water. Emulsions are a type of colloid where one liquid is dispersed in another. Water and oil are a common example of an emulsion, where the two liquids do not mix naturally but can be forced to form a stable mixture with the help of an emulsifying agent.
What is the atomic number of a mystery element that has 6 protons, 6 electrons, and 6 neutrons?
- A. 6
- B. 12
- C. 18
- D. Not enough information
Correct Answer: A
Rationale: The atomic number of an element is equal to the number of protons in its nucleus. Since the mystery element has 6 protons, its atomic number is also 6. The number of neutrons and electrons does not affect the atomic number. Protons determine the element's identity, while neutrons and electrons affect its mass and charge, respectively. Therefore, choice A, 6, is the correct answer.