Question

Which example indicates that a chemical change has occurred? *
1 point
A. When two aqueous solutions are mixed, a precipitate is formed.
B. As ammonium nitrate dissolves in water causes the temperature to decrease.
C. Alcohol evaporates when left in an open container.
D. Water is added to blue copper(II) chloride solution. The resulting mixture if lighter blue in color.

Answer 1

Answer:

A. When two aqueous solutions are mixed, a precipitate is formed.

Explanation:

The precipitate (a solid substance that falls from the liquid) is the result of a chemical reaction taking place between the liquids.

The other three answer choices are indicative of physical changes (temperature change, phase change, color change).

Answer 2

When two aqueous solutions are mixed, a precipitate is formed indicates that a chemical change has occurred.  

Hence, option A is correct answer.

What is Chemical change ?

Chemical change are those changes in which substance changes chemical composition. These changes are permanent changes. In chemical change new substances formed and in chemical change substances can not get back into its original form. It is irreversible change.

What is Physical change ?

Physical changes are those changes in which substance changes physical properties only. Properties like temperature, pressure, shape, color, size, state (solid, liquid and gas). These changes are temporary in nature. In physical change no new substances formed. It is reversible change.

Now, check all the options one by one:

Option (A): When two aqueous solutions are mixed, a precipitate is formed is a chemical change. Since precipitation indicate a chemical reaction (that is double displacement reaction).

Option (B): As ammonium nitrate dissolved in water causes the temperature to decrease is a physical change because heat energy is absorbed here and it is a endothermic reaction.

Option (C): Alcohol evaporates when left in an open container is a physical change because evaporation is a physical change as it changes the state from liquid state to gas state.

Option (D): Water is added to blue copper (II) chloride solution. The resulting mixture if lighter blue in color is a physical change as properties like change in color is physical change.  

Thus, from above conclusion we can say that When two aqueous solutions are mixed, a precipitate is formed indicates that a chemical change has occurred.  

Hence, option A is correct answer.

Learn more about physical and chemical change here: https://brainly.com/question/17166994

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