Which of the following is an example of an exothermic reaction?
A. Melting ice
B. Burning wood
C. Cooking an egg
D. Dissolving sugar in water
Exothermic reactions are reactions that release energy in the form of heat, light, or sound. Burning wood is an example of an exothermic reaction because it releases heat and light. As the wood reacts with oxygen in the air, it undergoes a combustion reaction that releases energy in the form of heat and light. Melting ice is an endothermic reaction because it requires energy input to melt the solid ice into liquid water. Cooking an egg is a chemical reaction that involves denaturing the proteins in the egg, but it is not necessarily exothermic or endothermic. Dissolving sugar in water is also not an example of an exothermic reaction because it does not release energy in the form of heat, light, or sound.
Therefore, the Correct Answer is B.
More Questions on TEAS 7 Science
-
Q #1: Which of the following is a chemical property of a substance?
A. Density
B. Melting point
C. Boiling point
D. Reactivity with acid
Answer Explanation
Chemical properties are characteristics of a substance that describe its ability to undergo a chemical change or reaction with another substance.
Reactivity with acid is a chemical property because it describes how a substance will react with an acid to produce a new substance. Density, melting point, and boiling point are physical properties that describe how a substance behaves under certain conditions but do not involve a chemical change or reaction.
-
Q #2: A researcher collects data on the number of cars passing through a busy intersection at different times of the day for a month. This data would be most useful to analyze which of the following:
A. traffic paterns during rush hour
B. pedestrian movement during the day
C. air pollution levels in the area
D. noise levels in the area
Answer Explanation
The data collected by the researcher on the number of cars passing through a busy intersection at different times of the day for a month would be most useful to analyze traffic paterns during rush hour.
-
Q #3: What are the steps involved in the scientific method?
A. Observation, hypothesis, prediction, experimentation, analysis, conclusion.
B. Hypothesis, observation, prediction, experimentation, analysis, conclusion.
C. Prediction, observation, experimentation, analysis, conclusion, hypothesis.
D. Observation, data collection, analysis, experimentation, hypothesis, conclusion.
Answer Explanation
The scientific method is a systematic approach used to answer questions or test hypotheses about the natural world. The steps involved in the scientific method are:
- Observation: This is the first step in the scientific method. It involves observing a phenomenon or a problem and gathering information about it.
- Hypothesis: After making an observation, a scientist forms a hypothesis, which is a tentative explanation for the phenomenon or problem.
- Prediction: Based on the hypothesis, the scientist makes a prediction about what will happen in an experiment or what they will observe.
- Experimentation: The scientist designs and conducts an experiment to test the hypothesis and prediction.
- Analysis: The data collected from the experiment are analyzed to determine if they support or refute the hypothesis.
- Conclusion: Based on the analysis of the data, the scientist draws a conclusion about whether the hypothesis is supported or refuted.
Option b) is incorrect because it starts with hypothesis before observation. Option c) is incorrect because prediction comes before experimentation. Option d) is incorrect because hypothesis comes after observation and data collection.
