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What type of reaction is described by the following equation? ZnBr2(aq) + 2KOH(aq) → Zn(OH)2(s) + 2KBr(aq)

A. Synthesis

B. Decomposition

C. Single-Replacement

D. Double-Replacement

Answer Explanation:

In this reaction, two elements are trading places hence double-replacement. In the reactants, zinc and bromide ions are together, and potassium and hydroxide ions are together. In the products, zinc and hydroxide ions are together, and potassium and bromide ions are together.

Therefore, the Correct Answer is D.

More Questions on TEAS 7 Science

  • Q #1: _____ is dependent not only on the temperature, but also on the amount of substance available.

    A. Condensation

    B. Deposition

    C. Evaporation

    D. Melting

    Answer Explanation

    Unlike condensation, deposition, and melting, evaporation is dependent not only on the temperature, but also on the amount of a substance available.

    Condensation is the change of a gas or vapor to a liquid. A change in the pressure and the temperature of a substance causes this change. The condensation point is the same as the boiling point of a substance. It is most noticeable when there is a large temperature difference between an object and the atmosphere. Condensation is also the opposite of evaporation.

    Evaporation is the change of a liquid to a gas on the surface of a substance. This is not to be confused with boiling, which is a phase transition of an entire substance from a liquid to a gas. The evaporation point is the same as the freezing point of a substance. As the temperature increases, the rate of evaporation also increases. Evaporation depends not only on the temperature, but also on the amount of substance available.

    Freezing is the change of a liquid to a solid. It occurs when the temperature drops below the freezing point. The amount of heat that has been removed from the substance allows the particles of the substance to draw closer together, and the material changes from a liquid to a solid. It is the opposite of melting.

    Melting is the change of a solid into a liquid. For melting to occur, enough heat must be added to the substance. When this is done, the molecules move around more, and the particles are unable to hold together as tightly as they can in a solid. They break apart, and the solid becomes a liquid.

    Sublimation is a solid changing into a gas. As a material sublimates, it does not pass through the liquid state. An example of sublimation is carbon dioxide, a gas, changing into dry ice, a solid. It is the reverse of deposition.

    Deposition is a gas changing into a solid without going through the liquid phase. It is an uncommon phase change. An example is when it is extremely cold outside and the cold air comes in contact with a window. Ice will form on the window without going through the liquid state.

  • Q #2: What standard is used to make comparisons in experiments?

    A. Sample size

    B. Control group

    C. Dependent variable

    D. Independent variable

    Answer Explanation

    A control group is a factor that does not change during an experiment. Due to this, it is used as a standard for comparison with variables that do change such as a dependent variable.

    Recall that these make up the scientific method, described below:

    • Problem: The question created because of an observation. Example: Does the size of a plastic object affect how fast it naturally degrades in a lake?
    • Research: Reliable information available about what is observed. Example: Learn how plastics are made and understand the properties of a lake.
    • Hypothesis: A predicted solution to the question or problem. Example: If the plastic material is small, then it will degrade faster than a large particle.
    • Experiment: A series of tests used to evaluate the hypothesis. Experiments consist of an independent variable that the researcher modifies and a dependent variable that changes due to the independent variable. They also include a control group used as a standard to make comparisons. 
      • Example: Collect plastic particles both onshore and offshore of the lake over time. Determine the size of the particles and describe the lake conditions during this time period.
    • Observe: Analyze data collected during an experiment to observe patterns. 
      • Example: Analyze the differences between the numbers of particles collected in terms of size.
    • Conclusion: State whether the hypothesis is rejected or accepted and summarize all results.
    • Communicate: Report findings so others can replicate and verify the results.

  • Q #3: If a person smells something sweet, what form of information is this initially perceived as in the nervous system?

    A. Cognitive

    B. Integrative

    C. Motor

    D. Sensory

    Answer Explanation

    A sensory nerve is a nerve that carries sensory signals from the external environment to the brain to the central nervous system. It is also an afferent nerve, long dendrites of sensory neurons, which sends sensory information towards the central nervous system (CNS). This information is what is sensed, using the five senses from external environment, sight, sound, smell, taste, and touch.

    Motor nerves have only efferent fibers, long axons of motor neurons, that carry impulses away from the CNS to the effectors, which are typically tissues and muscles of the body.

    Interneurons are nerve cells that act as a bridge between motor and sensory neurons in the CNS. These neurons help form neural circuits, which helps neurons communicate with each other.