Nokea
What are bases or alkaline solutions known as?
- A. Hydrogen acceptors
- B. Solutions of low pH
- C. Hydrogen donors
- D. Amphoteric
Correct Answer: A
Rationale: Bases or alkaline solutions are substances that can accept protons (H+ ions), making them hydrogen acceptors. When a base reacts with an acid, it accepts a proton to form water, hence neutralizing the acid. This property distinguishes bases from acids, which donate protons (H+ ions). Therefore, the correct answer is that bases or alkaline solutions are known as hydrogen acceptors.
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How many hydrogen atoms are present in the reactants?
- A. 2
- B. 4
- C. 1
- D. None of the above
Correct Answer: B
Rationale: To determine the number of hydrogen atoms in the reactants, we need to examine the chemical formula of the reactants. If the formula contains hydrogen atoms, we count them to find the total. In this case, the correct answer is 4 because there are 4 hydrogen atoms present in the reactants. The chemical formula in the reactants indicates the presence of 4 hydrogen atoms. It is crucial to pay close attention to the elements and their quantities in chemical reactions to ensure accurate analysis and understanding of reactants and products.
What occurs to an atom that has a positive charge?
- A. Gained an electron.
- B. Lost an electron.
- C. Gained a proton.
- D. Lost a proton.
Correct Answer: B
Rationale: When an atom has a positive charge, it indicates that it has lost an electron. Electrons carry a negative charge, so the absence of an electron leads to a net positive charge for the atom. Gaining a proton or losing a proton would modify the atom's identity by changing its atomic number, but it would not directly result in a positive charge. Therefore, the correct response is that the atom lost an electron to acquire a positive charge.
What is a benefit of water's ability to make hydrogen bonds?
- A. Lack of cohesiveness
- B. Low surface tension
- C. Use as a nonpolar solvent
- D. High specific heat
Correct Answer: D
Rationale: The correct answer is D - High specific heat. Water's ability to make hydrogen bonds leads to a high specific heat capacity, which allows it to absorb and release large amounts of heat with minimal temperature change. This property is crucial for maintaining stable temperatures in living organisms and aquatic environments. High specific heat helps regulate body temperature in organisms and prevents sudden temperature fluctuations in water bodies, providing an essential benefit for various biological processes.
Which of the following must be present in order to be considered an organic molecule?
- A. H
- B. O
- C. N
- D. C
Correct Answer: D
Rationale: To be considered an organic molecule, carbon (C) must be present. Organic molecules are primarily composed of carbon atoms bonded to hydrogen (H) atoms, along with other elements like oxygen (O), nitrogen (N), sulfur, and phosphorus. Carbon is the backbone of organic compounds due to its unique bonding properties and ability to form long and complex chains, making it an essential element in organic chemistry. While hydrogen, oxygen, and nitrogen are commonly found in organic molecules, it is the presence of carbon that defines a compound as organic. Without carbon, a molecule cannot be classified as organic, regardless of the presence of other elements.
What defines the atomic number of an element?
- A. Number of neutrons
- B. Number of protons
- C. Number of electrons
- D. Number of isotopes
Correct Answer: B
Rationale: The atomic number of an element is defined by the number of protons in the nucleus of its atom. This number uniquely identifies an element and determines its chemical properties. Neutrons and electrons are also present in the atom and are essential, but the atomic number specifically refers to the number of protons. The number of neutrons is not the atomic number but contributes to the isotope of an element. The number of electrons can vary, but the number of protons remains constant for a specific element.