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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.
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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 can be predicted by using the periodic table?
- A. The properties of each of the elements
- B. The charges of polyatomic ions
- C. The number of isotopes in each element
- D. The potential for the discovery of new elements
Correct Answer: A
Rationale: The periodic table is a fundamental tool in chemistry that organizes elements based on their properties. By using the periodic table, scientists can predict the properties of each element. The arrangement of elements in the table groups together elements with similar characteristics, allowing for the prediction of various properties such as reactivity, atomic size, and electronegativity. These predictions are possible because elements in the same group or period exhibit similar chemical behaviors. Therefore, the correct answer is A: The properties of each of the elements.
What volume of silver metal will weigh exactly 2500.0 g? The density of silver is 10.5 g/cm³.
- A. 26250 cm³
- B. 238.1 cm³
- C. 0.0042 cm³
- D. None of the above
Correct Answer: B
Rationale: To determine the volume of silver, we use the formula: Volume = Mass / Density. Substituting the given values, Volume = 2500.0 g / 10.5 g/cm³ = 238.1 cm³. Therefore, the correct answer is 238.1 cm³, which represents the volume of silver metal weighing precisely 2500.0 g at a density of 10.5 g/cm³.
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.
Which statement is true regarding combination reactions?
- A. Involve only one reactant.
- B. Involve an element and an ionic compound.
- C. Form only one product.
- D. Require oxygen gas.
Correct Answer: C
Rationale: In a combination reaction, two or more substances combine to form a single product. This reaction type does not always involve only one reactant (choice A), an element and an ionic compound (choice B), or require oxygen gas (choice D). The true characteristic of combination reactions is that they form only one product, making choice C the correct answer.