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A block on your desk acts as a paperweight with measurements of 3 cm by 4 cm by 6 cm. The block has a mass of 184.32 g. What is its density?
- A. 13,271.04 g/cm³
- B. 2.56 g/cm³
- C. 0.39 g/cm³
- D. None of the above
Correct Answer: B
Rationale: Density is calculated by dividing mass by volume. To find the volume of the block, multiply its dimensions (3 cm x 4 cm x 6 cm = 72 cm³). Dividing the mass (184.32 g) by the volume (72 cm³) gives a density of 2.56 g/cm³. Therefore, the correct answer is B.
You may also like to solve these questions
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 charge on potassium in the compound KCl?
- A. -1
- B. +1
- C. -2
- D. +2
Correct Answer: B
Rationale: In the compound KCl, the overall charge must be zero since it is a neutral compound. Chlorine (Cl) typically has a charge of -1 in ionic compounds. Therefore, for the compound to be neutral, potassium (K) must have a charge of +1 to balance the -1 charge of chlorine. This results in a total charge of 0 for the compound. Thus, the correct answer is +1. The positively charged potassium ion (K+) combines with the negatively charged chloride ion (Cl-) to form an electrically neutral compound, potassium chloride (KCl).
What are buffers?
- A. Proteins
- B. Solutions that resist changes in pH
- C. Catalysts in a reaction
- D. Inhibitors in a reaction
Correct Answer: B
Rationale: Buffers are solutions that resist changes in pH by neutralizing small amounts of acids or bases that may be added to them. They help maintain a stable pH environment and are commonly used in various biological and chemical processes to prevent drastic changes in acidity or alkalinity. Buffers do not act as catalysts or inhibitors in reactions. Their main purpose is to stabilize pH levels and ensure a relatively constant pH within a system, making them essential in maintaining the proper conditions for many biological reactions and processes.
In an experiment, a student tests three unknown fluids with the following measurements: Fluid A: m=2060g, V=2000mL, Fluid B: m=672g, V=850mL, and Fluid C: m=990g, V=1100mL. Arrange the liquids in the correct order of how they would separate in a beaker from bottom to top.
- A. A, B, C
- B. B, C, A
- C. C, A, B
- D. B, A, C
Correct Answer: B
Rationale: To determine the order in which the liquids will separate in a beaker, we must consider their densities, calculated using the formula Density = Mass (m) / Volume (V). The liquid with the higher density will settle at the bottom, while the liquid with the lower density will rise to the top. For the given fluids, Fluid A has a density of 1.03 g/mL (2060 g / 2000 mL), Fluid B has a density of approximately 0.79 g/mL (672 g / 850 mL), and Fluid C has a density of approximately 0.90 g/mL (990 g / 1100 mL). Based on these calculations, the correct order of the fluids from bottom to top, according to increasing density, is Fluid B, Fluid C, and Fluid A.
Which type of bond involves atoms gaining or losing electrons?
- A. Ionic
- B. Covalent
- C. Both
- D. Neither
Correct Answer: A
Rationale: Ionic bonds involve the transfer of electrons between atoms, leading to one atom gaining electrons (becoming negatively charged) while the other loses electrons (becoming positively charged). This results in the formation of ions that are held together by electrostatic forces, creating an ionic bond. In a covalent bond, atoms share electrons rather than gaining or losing them, making option A, 'Ionic,' the correct answer to this question. Therefore, the correct answer is 'Ionic,' as it specifically involves gaining or losing electrons to form a bond.