Tag: introduction to physical and chemical changes

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Multiple choice chemistry phenomena around us comparison between physical and chemical changes introduction to physical and chemical changes change around us

Choose the incorrect statement :

  1. Physical change is reversible

  2. Physical change results in the formation of new substances

  3. Chemical change is permanent

  4. Physical change is accompanied by energy change
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Physical change does not lead to formation of new substances but only chemical changes can produce new substances.

Multiple choice chemistry phenomena around us comparison between physical and chemical changes introduction to physical and chemical changes change around us

Changes are of _________ kinds.

  1. three

  2. two

  3. four

  4. five
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Changes are of two kinds: Physical and chemical changes.
A physical change in a substance does not change what the substance is.
Where as in a chemical change, where there is a chemical reaction, anew substance is formed and energy is either given off or absorbed.

Multiple choice chemistry phenomena around us comparison between physical and chemical changes introduction to physical and chemical changes change around us

Physical changes require _______ energy than chemical changes.

  1. less

  2. more

  3. equal amount of

  4. very high amount of
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Physical changes require less energy than chemical energies, as they does not involve in making and breaking of bonds as in the case of chemical bonds, which require a lot of energy.

Multiple choice chemistry phenomena around us comparison between physical and chemical changes introduction to physical and chemical changes change around us

What property stays the same during physical and chemical changes?

  1. Density

  2. Shape

  3. Mass

  4. Arrangement of particle
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Since the law of conservation of mass is valid under all circumstances, hence, mass always remains the same, whether a substance undergoes physical change or chemical change. 

Multiple choice chemistry phenomena around us comparison between physical and chemical changes introduction to physical and chemical changes change around us

Which of the following is an example of chemical change?

  1. Filling up a balloon with hot air.

  2. Taking a glass of water and freezing it by placing it in the freezer.

  3. A plant collecting sunlight and turning it into food.

  4. Your dog ripping up your homework.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A plant collecting sunlight and turning it into food is a photosynthesis reaction which is an example of a photochemical reaction. This is a chemical change. 

Multiple choice chemistry phenomena around us comparison between physical and chemical changes introduction to physical and chemical changes change around us

What characteristic best describes what happen during a physical change?

  1. Composition changes.

  2. Composition stays the same.

  3. Form stays the same.

  4. Mass is lost.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation
Physical changes are changes affecting the form of a chemical substance, but not its chemical composition. 
Physical changes occur when objects or substances undergo a change that does not change their chemical composition.
Multiple choice chemistry phenomena around us comparison between physical and chemical changes introduction to physical and chemical changes change around us

Common chemical changes are :

  1. change in temperature

  2. formation of precipitate

  3. formation of bubbles

  4. all of above
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A change in temperature is characteristic of a chemical change. When the reactants are mixed, the temperature change caused by the reaction is an indicator of a chemical change. 


The formation of a precipitate may be one of the most common signs of a chemical reaction taking place. The formation of bubbles, or rather a gas, is another indicator of a chemical reaction taking place. When bubbles form, a temperature change could also be taking place.

So, the correct option is $D$

Multiple choice chemistry phenomena around us comparison between physical and chemical changes introduction to physical and chemical changes change around us

Heating of ammonium chloride solution is a:

  1. physical change

  2. chemical change

  3. depends on temperature

  4. can't say
Reveal answer Fill a bubble to check yourself
A,B Correct answer
Explanation

Solid ammonium chloride vapourizes to form gaseous ammonium chloride. This is a physical change. Ammonium chloride is partially dissociated. This a chemical change. The products ammonia and chlorine recombine to form ammonium chloride. This is also a chemical change.

Multiple choice chemistry phenomena around us comparison between physical and chemical changes introduction to physical and chemical changes change around us

Burning of candle is a :

  1. physical change

  2. chemical change

  3. both a and b

  4. none of these
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

On burning candle, wax melts which is a physical change. Also, the wax near the flame burns and gives $CO _2$, soot, light and heat which is a chemical change. Hence, burning of candle is a physical as well as chemical change.