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What is the density of a block on your desk that acts as a paperweight? The block measures 3cm by 4cm by 6cm and has a mass of 184.32g.
- A. 13.27 g/cm3
- B. 2.56 g/cm3
- C. 0.39 g/cm3
- D. None of the above.
Correct Answer: B
Rationale: To calculate density, you use the formula: Density = Mass/Volume. First, calculate the volume of the block by multiplying its dimensions: 3cm x 4cm x 6cm = 72 cm3. Next, divide the mass (184.32g) by the volume (72 cm3) to find the density. Density = 184.32g / 72 cm3 = 2.56 g/cm3. Therefore, the correct answer is B, with a density of 2.56 g/cm3.
You may also like to solve these questions
Will solids always sink in liquids?
- A. True, because solids are hard while liquids are not.
- B. True, because solids are heavier than liquids.
- C. False, because solids have a smooth surface, so they will float.
- D. False, it depends on the density of the solid and liquid.
Correct Answer: D
Rationale: The statement 'solids will always sink in liquids' is not always true. Whether a solid sinks or floats in a liquid depends on the relative densities of the solid and the liquid. If the density of the solid is greater than the density of the liquid, the solid will sink. Conversely, if the density of the solid is less than the density of the liquid, the solid will float. Therefore, the correct answer is 'False, it depends on the density of the solid and liquid.'
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.
When propane is reacted in the presence of oxygen gas, the products of this combustion reaction are:
- A. C + H2
- B. CH2 + H2O
- C. CO2 + H2
- D. CO2 + H2O
Correct Answer: D
Rationale: When propane undergoes combustion in the presence of oxygen, it forms carbon dioxide (CO2) and water (H2O). The balanced chemical equation for this reaction is: C3H8 + 5O2 -> 3CO2 + 4H2O. This means that three molecules of carbon dioxide and four molecules of water are produced when one molecule of propane reacts with five molecules of oxygen. Therefore, option D (CO2 + H2O) is the correct answer.
Which type of RNA is used to carry the genetic code copied from DNA?
- A. mRNA
- B. tRNA
- C. rRNA
- D. None of the above
Correct Answer: A
Rationale: The correct answer is mRNA (messenger RNA). mRNA is responsible for carrying the genetic information copied from DNA in the cell nucleus to the ribosomes in the cytoplasm where protein synthesis occurs. This process is known as transcription. mRNA acts as a messenger, delivering the genetic instructions to the ribosomes for protein synthesis. In contrast, tRNA (transfer RNA) brings specific amino acids to the ribosome during translation, helping to assemble the protein chain. rRNA (ribosomal RNA) forms a structural and catalytic part of the ribosome itself, aiding in protein synthesis. Therefore, among the options provided, mRNA is the RNA type directly involved in carrying the genetic code from DNA for protein production.
What is the density of carbon tetrachloride if a flask weighing 345.8 g is filled with 225 mL of the liquid, and the total weight of the flask and liquid is 703.55 g?
- A. 1.59 g/mL
- B. 2.76 g/mL
- C. 1.4 g/mL
- D. None of the above
Correct Answer: A
Rationale: To find the density of carbon tetrachloride, we first need to determine the weight of the liquid only. The weight of the liquid can be calculated by subtracting the weight of the empty flask from the total weight of the flask and liquid: 703.55 g - 345.8 g = 357.75 g. Now, using the volume of the liquid (225 mL) and its weight (357.75 g), we can calculate the density: Density = Mass/Volume = 357.75 g / 225 mL ĉ� 1.59 g/mL. Therefore, the correct answer is A, 1.59 g/mL.