What is the product of the complete combustion of propane (C3H8)?

Correct Answer: A

Rationale: The complete combustion of propane (C3H8) results in the production of carbon dioxide (CO2) and water. When a hydrocarbon such as propane undergoes complete combustion, the carbon atoms combine with oxygen to form CO2. This makes choice A, CO2, the correct answer. Choices B, C, and D are incorrect as CO is carbon monoxide, CH4 is methane, and C is elemental carbon, none of which are the primary product of the complete combustion of propane.

Correct Answer: D

Rationale: In CH4 (methane), carbon is bonded to four hydrogen atoms. Hydrogen has an oxidation state of +1. Since the overall charge of CH4 is 0, the oxidation state of carbon must be -4 to balance the charges. Each hydrogen contributes an oxidation state of +1, resulting in a total of +4 from hydrogen atoms. To achieve a total oxidation state of 0 for the molecule, carbon must have an oxidation state of -4 to offset the contribution from hydrogen. Therefore, the correct answer is -4. Choices A, B, and C are incorrect: +1 is the oxidation state of hydrogen, -1 is not the oxidation state of carbon in methane, and +2 is not the correct oxidation state of carbon in CH4.

Correct Answer: B

Rationale: The pH scale measures the acidity or basicity of a solution. A pH of 7 is considered neutral, indicating that the concentration of hydrogen ions (H+) is equal to the concentration of hydroxide ions (OH-) in the solution. A pH ranging from 0 to 6.9 signifies acidity, while a pH from 7.1 to 14 signifies alkalinity. Therefore, a neutral solution has a pH value of 7. Choice A (0) represents a highly acidic solution, Choices C (14) and D (-7) are outside the valid pH range and do not correspond to a neutral solution.

Correct Answer: C

Rationale: - Messenger RNA (mRNA) carries the genetic information from DNA in the cell's nucleus to the ribosomes in the cytoplasm, where protein synthesis occurs. - Ribosomal RNA (rRNA) is a component of the ribosomes where protein synthesis takes place. - Transfer RNA (tRNA) is responsible for bringing amino acids to the ribosomes during protein synthesis. - Deoxyribonucleic acid (DNA) is the genetic material that contains the instructions for building and maintaining an organism. DNA is transcribed into mRNA before being translated into proteins.

Correct Answer: A

Rationale: Sodium hydroxide (NaOH) is a strong base commonly used in cleaning products due to its effectiveness in breaking down grease and fats. It is known for its corrosive properties and is commonly found in drain cleaners and oven cleaners. While ammonium hydroxide, calcium hydroxide, and potassium hydroxide are also bases, they are not as strong as sodium hydroxide and are not as commonly used in cleaning products. Ammonium hydroxide is more commonly found in household cleaning products for its disinfectant properties, calcium hydroxide is used in agriculture and construction, and potassium hydroxide is often used in industries like soap manufacturing and biodiesel production.