Nokea
What is the primary function of the large intestine?
- A. Digesting and absorbing nutrients
- B. Storing and mixing food
- C. Breaking down carbohydrates
- D. Absorbing water and electrolytes
Correct Answer: D
Rationale: The primary function of the large intestine is to absorb water and electrolytes from the indigestible food matter that passes through it. This absorption process aids in the formation of solid waste (feces) before it is excreted from the body. Choices A, B, and C are incorrect because the large intestine does not primarily digest and absorb nutrients, store and mix food, or break down carbohydrates. These functions are primarily carried out by the small intestine.
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Which of the following best describes a balanced force acting on an object?
- A. The object remains at rest
- B. The object moves with constant velocity
- C. The object accelerates
- D. The object's mass changes
Correct Answer: B
Rationale: When a balanced force acts on an object, the net force is zero, resulting in no acceleration. This means that the object will continue to move with a constant velocity if it was already in motion or remain at rest if it was initially stationary. Choice A is incorrect because the object can also move with constant velocity. Choice C is incorrect as acceleration only occurs when an unbalanced force is applied. Choice D is incorrect as the mass of an object is not affected by the balance of forces acting on it.
What does half-life refer to?
- A. Radioactive intensity to completely disappear
- B. The number of neutrons in a nucleus to double
- C. The number of protons in a nucleus to change
- D. An isotope to decay by half of its initial quantity
Correct Answer: D
Rationale: Half-life refers to the time it takes for half of the radioactive atoms in a sample to decay. This means that after one half-life, half of the initial quantity of the radioactive substance will have decayed. Choice A is incorrect because radioactive intensity doesn't completely disappear during half-life. Choice B is incorrect as half-life doesn't refer to the number of neutrons doubling. Choice C is incorrect as half-life doesn't relate to the number of protons changing.
Which group of elements is known for their reactivity and ability to form strong bonds with other elements?
- A. Noble gases
- B. Halogens
- C. Alkali metals
- D. Transition metals
Correct Answer: B
Rationale: Halogens are a group of elements in the periodic table known for their high reactivity and ability to form strong bonds with other elements. They possess seven valence electrons, requiring only one more electron to achieve a stable electron configuration, making them highly reactive. Halogens readily form compounds with other elements by gaining an electron to achieve a full outer shell, resulting in the formation of strong covalent bonds. Noble gases (option A), on the other hand, are known for their inertness and stable electron configurations, making them unlikely to form bonds. Alkali metals (option C) are highly reactive but do not form bonds as strong as halogens. Transition metals (option D) are recognized for their variable oxidation states and ability to create complex ions but are not as reactive as halogens when it comes to bond formation.
What is the general formula for an alkyl halide?
- A. Câ‚™Hâ‚‚â‚™
- B. CₙH₂ₙ₊₂
- C. Câ‚™H₂ₙ₊â‚X
- D. Câ‚™Hâ‚‚â‚™O
Correct Answer: C
Rationale: The correct answer is option C, 'Câ‚™H₂ₙ₊â‚X.' This is the general formula for an alkyl halide, where X represents a halogen atom (such as fluorine, chlorine, bromine, or iodine), and the hydrocarbon chain is represented by Câ‚™H₂ₙ₊â‚. Option A, 'Câ‚™Hâ‚‚â‚™,' is incorrect because it does not account for the presence of a halogen atom. Option B, 'Câ‚™H₂ₙ₊₂,' is incorrect as it represents an alkene, not an alkyl halide. Option D, 'Câ‚™Hâ‚‚â‚™O,' is also incorrect as it suggests the presence of oxygen, which is not characteristic of alkyl halides.
Which of the following substances is an example of an acidic gas?
- A. Nitrogen (Nâ‚‚)
- B. Carbon dioxide (COâ‚‚)
- C. Sulfur dioxide (SOâ‚‚)
- D. Oxygen (Oâ‚‚)
Correct Answer: C
Rationale: The correct answer is C, Sulfur dioxide (SOâ‚‚). Sulfur dioxide is an acidic gas because when dissolved in water, it forms sulfurous acid, which imparts acidic properties. Nitrogen (Nâ‚‚), carbon dioxide (COâ‚‚), and oxygen (Oâ‚‚) are not considered acidic gases. Nitrogen is a neutral gas, carbon dioxide forms a weakly acidic solution when dissolved in water, and oxygen is a neutral gas.