in the reaction 2h2 o2 2h2o how many moles of oxygen are required to react completely with 4 moles of hydrogen

ATI TEAS 7

TEAS Test 7 science quizlet

1. In the reaction 2H2 + O2 → 2H2O, how many moles of oxygen are required to react completely with 4 moles of hydrogen?

A. 1
B. 2
C. 3
D. 4

Correct answer: B

Rationale: The balanced chemical equation indicates that 2 moles of H2 react with 1 mole of O2 to produce 2 moles of H2O. To determine how many moles of O2 are required to react with 4 moles of H2, you can use the mole ratio from the balanced equation: 2 moles of H2 react with 1 mole of O2. Therefore, to react completely with 4 moles of H2, you would need 2 moles of O2 (4 moles H2 ÷ 2 moles H2 per 1 mole O2). Hence, 2 moles of oxygen are required to react completely with 4 moles of hydrogen. Choices A, C, and D are incorrect because they do not reflect the correct stoichiometry as defined by the balanced chemical equation.

2. What is the term for the process of a gas changing directly into a solid?

A. Condensation
B. Deposition
C. Sublimation
D. Evaporation

Correct answer: B

Rationale: The correct term for the process of a gas changing directly into a solid is deposition. During deposition, gas particles lose energy and transition directly into the solid state without passing through the liquid phase. Sublimation, on the other hand, is the process in which a solid changes directly into a gas without going through the liquid phase. Condensation is the process where gas changes into a liquid state. Evaporation, on the contrary, is the conversion of a liquid to a gas. Therefore, the correct answer is B, deposition.

3. Salts like sodium iodide (NaI) and potassium chloride (KCl) use what type of bond?

A. Ionic bonds
B. Disulfide bridges
C. Covalent bonds
D. London dispersion forces

Correct answer: A

Rationale: Salts like sodium iodide (NaI) and potassium chloride (KCl) use ionic bonds. Ionic bonds are formed between atoms with significantly different electronegativities, leading to the transfer of electrons from one atom to another. In the case of NaI and KCl, sodium (Na) and potassium (K) are metals that easily lose electrons to become positively charged ions, while iodide (I) and chloride (Cl) are nonmetals that readily accept electrons to become negatively charged ions. The attraction between the oppositely charged ions forms the ionic bond, which holds the compound together in a lattice structure. Disulfide bridges (option B) are covalent bonds formed between sulfur atoms in proteins, not in salts. Covalent bonds (option C) involve the sharing of electrons between atoms and are typically seen in molecules, not ionic compounds like salts. London dispersion forces (option D) are weak intermolecular forces that occur between all types of molecules but are not the primary type of bond in salts like NaI and KCl.

4. What presents the correct order of cellular respiration?

A. Glycolysis, Acetyl-CoA, Citric Acid Cycle, Electron Transport Chain
B. Citric Acid Cycle, Glycolysis, Acetyl-CoA, Electron Transport Chain
C. Glycolysis, Acetyl-CoA, Electron Transport Chain, Citric Acid Cycle
D. Glycolysis, Citric Acid Cycle, Electron Transport Chain, Acetyl-CoA

Correct answer: A

Rationale: The correct order of cellular respiration is Glycolysis, Acetyl-CoA, Citric Acid Cycle, and Electron Transport Chain. Glycolysis initiates the breakdown of glucose in the cytoplasm, leading to the formation of pyruvate. This pyruvate is then converted to Acetyl-CoA in the mitochondria, which enters the Citric Acid Cycle to generate energy-rich molecules like NADH and FADH2. Finally, the Electron Transport Chain, located in the inner mitochondrial membrane, utilizes these energy carriers to produce ATP through oxidative phosphorylation. Choice B is incorrect because it starts with the Citric Acid Cycle, which comes after Glycolysis. Choice C is incorrect as it places the Citric Acid Cycle before the Electron Transport Chain. Choice D is incorrect by placing Acetyl-CoA last instead of before the Citric Acid Cycle.

5. How did life most likely arise on Earth?

A. From simple organic molecules in a primordial soup
B. By spontaneous generation from non-living matter
C. Through the arrival of extraterrestrial life forms
D. We still don't know for sure

Correct answer: A

Rationale: The most widely accepted scientific theory for the origin of life on Earth is abiogenesis, which suggests that life arose from simple organic molecules in a primordial soup. This theory is supported by experiments such as the Miller-Urey experiment, which demonstrated that the basic building blocks of life could have formed under early Earth conditions. While there are other hypotheses and ongoing research in this field, the primordial soup theory is currently the most plausible explanation for the origin of life on Earth. Option B, spontaneous generation from non-living matter, has been disproven and is not considered a valid explanation. Option C, the arrival of extraterrestrial life forms, lacks evidence and is not a widely accepted theory. Option D, stating that we still don't know for sure, is true to some extent as the origin of life is a complex topic, but current scientific understanding leans towards abiogenesis from simple organic molecules in a primordial soup.