Petroleum is classified chemically as:
Answer: (D) a mixture
Explanation: Petroleum is a complex mixture of hydrocarbons and other organic compounds. It is not a pure substance, compound, or element.
Given: (52.6 cm) * (1.214 cm). What is the product expressed to the correct number of significant figures?
Answer: (C) 63.86 cm²
Explanation: When multiplying or dividing numbers, the result should have the same number of significant figures as the least precise number provided, which is 1.214 cm in this case.
Which measurement contains three significant figures?
Answer: (D) 8.08 cm
Explanation: The measurement 8.08 cm has three significant figures because all non-zero digits are significant, and the zero between them is also significant.
At the triple point of water, the degree of freedom is:
Answer: (B) one
Explanation: At the triple point of water, all three phases (solid, liquid, and gas) coexist in equilibrium. This means there is only one degree of freedom because pressure and temperature are fixed at that point.
Which of the following must be the same before and after a chemical reaction?
Answer: (D) Both (a) and (c) must be the same.
Explanation: The law of conservation of mass states that the total mass of substances before a chemical reaction must be equal to the total mass after the reaction. This means that the sum of the masses of all substances involved (a) and the number of atoms of each type involved (c) must be the same before and after the reaction.
In coulometry, the total charge contains both the faradaic charge and a blank resulting from:
Answer: (D) adsorption
Explanation: In coulometry, the total charge passed during an electrochemical reaction consists of the faradaic charge, which is due to the electrochemical reaction itself, and non-faradaic charge, which includes processes like adsorption and other surface phenomena.