Nokea
An atom has a mass of 16 and 6 protons. What element is it, and how many neutrons are there?
- A. Sulfur, 10
- B. Sulfur, 22
- C. Carbon, 10
- D. Carbon, 22
Correct Answer: C
Rationale: The atomic mass of an atom is the sum of its protons and neutrons. In this case, the atom has 6 protons. To find the number of neutrons, subtract the number of protons (6) from the atomic mass (16), resulting in 10 neutrons. Since the atom with 6 protons corresponds to Carbon (which has an atomic number of 6), the correct answer is Carbon, 10.
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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.
What is the density of a piece of cork with a volume of 23.5 cm³ and a mass of 5.7g?
- A. 0.243g/cm³
- B. 4.123g/cm³
- C. 133.95g/cm³
- D. None of the above
Correct Answer: A
Rationale: Density is calculated by dividing the mass of an object by its volume. In this case, the density of the cork can be calculated by dividing 5.7g by 23.5 cm³, resulting in a density of approximately 0.243g/cm³. Therefore, choice A, 0.243g/cm³, is the correct answer as it accurately represents the density of the cork based on the provided values.
What is a combustion reaction?
- A. It is endothermic.
- B. It substitutes one element for another.
- C. It always shares electrons.
- D. It is a reaction that involves oxygen.
Correct Answer: D
Rationale: A combustion reaction is a type of chemical reaction that involves a substance reacting with oxygen gas to produce heat and light. This reaction is exothermic, releasing energy in the form of heat and light. The correct answer is D because combustion reactions specifically involve oxygen as a reactant, leading to the production of heat and light as byproducts.
What is the mass of ethyl alcohol that will exactly fill a 200.0 mL container?
- A. 157.8 g
- B. 25.49 g
- C. 0.39 g
- D. None of the above
Correct Answer: A
Rationale: To determine the mass of ethyl alcohol required to fill a 200.0 mL container, we apply the formula Mass = Volume x Density. Given that the volume is 200.0 mL and the density of ethyl alcohol is 0.789 g/mL, the calculation becomes Mass = 200.0 mL x 0.789 g/mL = 157.8 g. Therefore, the correct answer is A, 157.8 g, as this is the mass of ethyl alcohol needed to completely occupy the 200.0 mL container.
What is the building block of proteins?
- A. Lipids
- B. Amino acids
- C. DNA
- D. Cells
Correct Answer: B
Rationale: Amino acids are the fundamental building blocks of proteins. Proteins are large biomolecules made up of one or more chains of amino acids. Each amino acid contains an amine group, a carboxylic acid group, and a side chain specific to each amino acid. When amino acids link together through peptide bonds, they form proteins. Lipids are a different type of biomolecule that includes fats, oils, and phospholipids. DNA is a nucleic acid that carries genetic information but is not directly involved in the structure of proteins. Cells are the basic structural and functional units of living organisms, not the building blocks of proteins.