ATI TEAS 7
Chemistry
1. What is the name for the process where a solid changes directly into a gas?
- A. Evaporation
- B. Sublimation
- C. Condensation
- D. Melting
Correct answer: B
Rationale: Sublimation occurs when a solid directly transforms into a gas without passing through a liquid phase.
2. The T wave on an ECG corresponds to:
- A. Atrial depolarization
- B. Ventricular depolarization
- C. Atrial repolarization
- D. Ventricular repolarization
Correct answer: D
Rationale: The T wave on an ECG corresponds to ventricular repolarization. During this phase, the ventricles are resetting electrically after contraction, preparing for the next heartbeat. Atrial depolarization is represented by the P wave, ventricular depolarization by the QRS complex, and atrial repolarization is typically hidden within the QRS complex. Therefore, option D, 'Ventricular repolarization,' is the correct choice when identifying the electrical activity represented by the T wave on an ECG.
3. Which term describes the resistance of a substance to being hammered into different shapes?
- A. Viscosity
- B. Ductility
- C. Malleability
- D. Conductivity
Correct answer: c
Rationale: Malleability refers to the resistance of a substance to being hammered or pressed into different shapes without breaking.
4. The process by which a solid changes directly into a liquid is called:
- A. Melting
- B. Condensation
- C. Sublimation
- D. Deposition
Correct answer: D
Rationale: While melting is a solid to liquid transition, deposition, also known as sublimation, refers to a gas directly changing into a solid.
5. Positron emission tomography (PET) scans utilize a key property of positrons for medical imaging. What is this property?
- A. High mass
- B. Positive charge
- C. Extreme stability
- D. Identical behavior to electrons
Correct answer: B
Rationale: The correct answer is B: 'Positive charge.' Positron emission tomography (PET) scans rely on the fact that positrons are positively charged particles. When a positron is emitted during radioactive decay, it quickly collides with an electron, resulting in annihilation and the release of two gamma rays in opposite directions. These gamma rays are detected by the PET scanner to create detailed images of the body's internal organs and tissues. The positive charge of positrons is crucial for this process to occur, making option B the correct choice.
6. Sunscreen protects the skin from harmful ultraviolet (UV) rays by
- A. Reflecting UV rays away from the skin
- B. Absorbing UV rays and converting them to heat
- C. Blocking UV rays completely
- D. Stimulating melanin production
Correct answer: B
Rationale: The correct answer is B: Absorbing UV rays and converting them to heat. Sunscreen contains ingredients that act as filters to absorb UV radiation before it reaches the skin. These filters then convert the UV rays into a less harmful form of energy, usually heat, which is then released from the body. This process helps prevent UV radiation from damaging the skin cells and causing sunburn or long-term skin damage. Reflecting UV rays away from the skin (A) and blocking UV rays completely (C) are not accurate functions of sunscreen. Additionally, stimulating melanin production (D) is not a direct way in which sunscreen protects the skin from UV rays.
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