Mometrix TEAS 7 science practice test

Correct Answer: B

Rationale: A) Incorrect. DNA is double-stranded, but RNA is typically single-stranded. B) Correct. DNA contains deoxyribose sugar, which lacks an oxygen atom on the 2' carbon of the sugar ring, while RNA contains ribose sugar, which has an additional hydroxyl group on the 2' carbon. C) Incorrect. RNA contains the nitrogenous base uracil, while DNA contains thymine. D) Incorrect. DNA and RNA have distinct structures and functions, so they are not identical molecules.

Correct Answer: A

Rationale: The density of a substance is calculated by dividing the mass of the substance by its volume. The formula for density is Density = Mass / Volume. This calculation allows us to determine how much mass is present in a given volume of a substance, making option A the correct choice. Choice B (Volume / Mass) is incorrect because density is defined as mass per unit volume, so mass should be the numerator. Choice C (Mass x Volume) is incorrect as this would result in a different unit of measurement and not represent density. Choice D (None of the above) is incorrect as there is a specific formula for calculating density, which is mass divided by volume.

Correct Answer: B

Rationale: Optical fibers can transmit light signals around bends primarily due to refraction. Refraction is the bending of light as it passes from one medium to another, such as from air to glass in an optical fiber. This bending allows the light signals to travel through the fiber even around bends, making optical fibers an efficient means of transmitting light signals over long distances. Reflection (Choice A) occurs when light bounces off a surface, which is not the primary mechanism allowing light to travel around bends in optical fibers. Diffraction (Choice C) refers to the bending of light waves around obstacles or openings, but it is not the main reason light signals can traverse bends in optical fibers. Polarization (Choice D) is the orientation of light waves in a specific plane, but it does not play a significant role in enabling light to navigate bends in optical fibers.

Correct Answer: C

Rationale: The pH of a solution can be calculated using the formula: pH = -log[H+]. Given that the hydrogen ion concentration is \(1 \times 10^{-9}\) M, the pH can be calculated as pH = -log(1 x 10^-9) = 9. Therefore, the correct answer is C) 9.

Correct Answer: C

Rationale: Thermal energy is the correct answer as it is associated with the random motion of particles in a substance. When particles move randomly, they generate heat energy, which is a form of thermal energy. Potential energy is stored energy that can be converted into other forms when released, such as kinetic energy. Mechanical energy is the sum of potential and kinetic energy in an object, which is not directly related to the random motion of particles. Chemical energy is energy stored in the bonds of chemical compounds and is not specifically related to the motion of particles.