How does the use of a catalyst affect the activation energy of a chemical reaction?
A. It increases the activation energy required for the reaction.
B. It decreases the activation energy required for the reaction.
C. It has no effect on the activation energy required for the reaction.
D. It increases the rate of reaction but has no effect on the activation energy.
The correct answer is choice B.
It decreases the activation energy required for the reaction.
A catalyst provides a new reaction pathway in which a lower activation energy is offered.
This allows more reactant molecules to collide with enough energy to surmount the smaller energy barrier, increasing the rate of reaction 2.
Choice A, It increases the activation energy required for the reaction, is not the correct answer because it describes the opposite effect of a catalyst.
Choice C, It has no effect on the activation energy required for the reaction, is not the correct answer because a catalyst does have an effect on activation energy.
Choice D, It increases the rate of reaction but has no effect on the activation energy, is not the correct answer because a catalyst increases the rate of reaction by decreasing the activation energy.
Therefore, the Correct Answer is B.
More Questions on TEAS 7 Science
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Q #1: Which type of lymphocyte is capable of killing tumor cells and infected cells without prior sensitization?.
A. Helper T cells.
B. B cells.
C. Natural killer cells.
D. Cytotoxic T cells .
Answer Explanation
Natural killer cells.
Natural killer (NK) cells are large granular lymphocytes that are capable of destroying cells infected by viruses or bacteria and susceptible tumor cells without prior sensitization and restriction by MHC antigens.
Helper T cells (choice A) are a type of white blood cell that helps other immune cells respond to infections but do not directly kill infected or tumor cells.
B cells (choice B) are a type of white blood cell that produces antibodies to fight infections but do not directly kill infected or tumor cells.
Cytotoxic T cells (choice D) are a type of white blood cell that can kill infected or tumor cells but require prior sensitization to do so.
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Q #2: What is the relationship between atomic mass and mass number?
A. They are the same.
B. Atomic mass is always greater than mass number.
C. Atomic mass and mass number are not related.
D. Atomic mass is very close to mass number but with some deviation in the decimal places.
Answer Explanation
Atomic mass is very close to mass number but with some deviation in the decimal places.
Atomic mass is also known as atomic weight and is the weighted average mass of an atom of an element based on the relative natural abundance of that element’s isotopes.
The mass number, on the other hand, is a count of the total number of protons and neutrons in an atom’s nucleus.
Choice A is incorrect because atomic mass and mass number do not mean the same thing.
Choice B is incorrect because atomic mass is not always greater than mass number.
Choice C is incorrect because atomic mass and mass number are related.
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Q #3: A nurse is conducting a research study to compare the effects of two different pain medications on postoperative patients. The nurse randomly assigns the patients to either receive medication A or medication B. Which of the following is the best way to ensure that the study is valid and reliable?
A. Use a large sample size and a standardized procedure for administering the medications.
B. Use a placebo group and a double-blind technique for giving the medications.
C. Use a matched-pairs design and a crossover technique for switching the medications.
D. Use a convenience sample and a pretest-posttest design for measuring the pain levels.
Answer Explanation
The correct answer is choice B.
Using a placebo group and a double-blind technique for giving the medications is the best way to ensure that the study is valid and reliable.
A placebo group helps control for the placebo effect, which can influence the results of a study.
A double-blind technique means that neither the patients nor the researchers know which medication is being given, reducing bias.
Choice A is not the best answer because while a large sample size and standardized procedure can increase reliability, they do not address validity.
Choice C is not the best answer because a matched-pairs design and crossover technique are useful for reducing variability but do not address validity.
Choice D is not the best answer because a convenience sample may not be representative and a pretest-posttest design does not control for extraneous variables.
