Which of the following best describes the result of using a catalyst in a chemical reaction?
The reaction is completed in a shorter amount of time.
A more desirable product is often formed.
A greater amount of heat energy is released by the reaction.
The yield of product is increased.
The Correct Answer is A
A catalyst is a substance that increases the rate of a chemical reaction without being consumed by the reaction.
As a result, the reaction is completed in a shorter amount of time.
Choice B is not correct because using a catalyst does not necessarily result in the formation of a more desirable product.
Choice C is not correct because using a catalyst does not necessarily result in the release of a greater amount of heat energy by the reaction.
Choice D is not correct because using a catalyst does not necessarily increase the yield of product.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is C
Explanation
In an experiment, the dependent variable is the variable that is being measured and is expected to change in response to changes in the independent variable(s).
In this case, the bag mass change is being measured and is expected to change in response to changes in the independent variable (sucrose concentration).
Choice A is incorrect because duration is not a variable in this experiment.
Choice B is incorrect because temperature is not a variable in this experiment.
Choice D is incorrect because sucrose concentration is an independent variable, not a dependent variable.
An independent variable is a variable that is manipulated by the experimenter to see how it affects the dependent variable.
Correct Answer is A
Explanation
The threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.
Most often, the threshold potential is a membrane potential value between –50 and –55 mV.
The membrane potential of a neuron is determined by the distribution of ions across the cell membrane.
At rest, the inside of a neuron is more negative than the outside due to the presence of negatively charged proteins and other molecules.
The movement of ions across the cell membrane can change the membrane potential.
For example, when sodium ions enter the cell, they make the inside of the cell more positive (less negative), causing depolarization.
Choice B is incorrect because -80 mV is below the typical threshold value for mammalian neurons.
Choice C is incorrect because +35 mV is above the typical threshold value for mammalian neurons.
Choice D is incorrect because 0 mV is above the typical threshold value for mammalian neurons.
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