Tag: physical changes

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Questions Related to physical changes

Multiple choice chemistry change around us physical changes changes and their classification physical changes

A mixture of sand and salt can be separated by:

  1. Sublimation

  2. Sieving

  3. Dissolving salt and sand mixture in water and then filtration

  4. Dissolving salt in water and then distillation
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Dissolving salt in water and then distillation
Process to separate sand and salt from the mixture :
Step 1: Add water to the mixture and stir until the salt dissolve.
Step 2: Turn your burner on and then keep the mixture over it.
Step 3: Pour the water mixture through a very fine strainer or cheese cloth filter . (Sand will remain in filter, salt and water will pass through it)
Step 4: Pour the water and salt mixture back into the burner . And allow the water to boil away and collect salt from there.

Multiple choice chemistry change around us physical changes changes and their classification physical changes

Match the columns


I II
(a) Physical change (i) Curdling of milk
(b) Chemical change (ii) Demagnetisation of magnets
(iii) Digestion of food
(iv) Crystallisation of substance
(v) Rusting of iron

  1. a - i, ii, iii, b - iv, v

  2. a - ii, iv, b - i, iii, iv

  3. a - ii, iv, b - i , iii, v

  4. a - iii, v, b - i, ii, iv
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

A change in which only the physical properties of the substance gets changed, while its chemical composition remains unchanged, is called a physical change. Crystallisation of substance and Demagnetisation of magnets comes under this change.
A change in which chemical composition and chemical properties of the reacting substances undergo a change is called a chemical change.
Curdling of milk, Digestion of food, Rusting of iron etc. comes under chemical change.

Multiple choice chemistry change around us physical changes changes and their classification physical changes

Which of the following  laboratory technique would not bring a physical change in the components of a mixture?

  1. Chromatography

  2. Precipitation

  3. Filtering

  4. Distillation
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Physical change would not be in the components of a mixture by Filtering.
Filtering just separates solids from liquids. It does not involve any phase change.

Multiple choice chemistry change around us physical changes changes and their classification physical changes

$Ice\underset {cooling}{\overset {heating}{\rightleftharpoons}} water \underset {cooling}{\overset {heating}{\rightleftharpoons}} steam$. Identify the type of change

  1. Physical change

  2. Chemical change

  3. Both physical and chemical changes

  4. None
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

In the given example, water only changes its state by the change in temperature, but its properties remain same hence it is an example of physical change not a chemical change.

Multiple choice chemistry change around us physical changes changes and their classification physical changes

Boiling water is a _____ change because _____.

  1. Physical, the gaseous water produced is chemically identical to the liquid water the process began with

  2. Physical, the water was disappeared

  3. Chemical, heat was required for the change

  4. Chemical, the process produced a gas
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Boiling water is a physical change because the gaseous water produced is chemically identical to the liquid water i.e both of them have the same molecular structure of the water.

Multiple choice chemistry change around us physical changes changes and their classification physical changes

According to the CRC's  the melting point of cadmium bromide is $868^{\circ}C$. Which of the following equations best describes what occurs when cadmium is heated to $868^{\circ}C$?

  1. $CdBr(s)\rightarrow CdBr(l)$
  2. $CdBr _{2}(s)\rightarrow CdBr _{2}(l)$
  3. $CdBr _{2}(s)\rightarrow Cd(s) + Br _{2}(g)$
  4. $CdBr _{2}(s)\rightarrow Cd^{2+}(aq) + 2Br^{-}(aq)$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Heating a solid substance to its melting point causes a phase transition from the solid state to the liquid state without chemical decomposition. Therefore, solid cadmium bromide transforms into liquid cadmium bromide at 868 degrees Celsius.

Multiple choice chemistry change around us physical changes changes and their classification physical changes

What kind of changes is undergone when an electric bulb glows?

  1. A physical change

  2. A chemical change

  3. Both a physical and a chemical change

  4. A permanent change
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When an electric bulb glows a physical change is observed. As the light produced by the electric bulb is due to the heating effect of the conductor. Even though there is an occurrence of temperature change since no new substances are produced it is considered to be a physical change.

Multiple choice chemistry change around us physical changes changes and their classification physical changes

Your lab partner mixed two colorless solutions in the test tube. He sees no observable changes in the resulting mixture and is unable to detect any change in temperature. Based on these observations, what type of reaction has taken place?

  1. A physical reaction

  2. A chemical reaction

  3. An exothermic reaction

  4. An endothermic Reaction
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When two solutions are mixed and no observable changes like evolution of gas or precipitate formation takes place then the reaction is reversible and the reaction is a physical reaction.

Ans :- A

Multiple choice chemistry change around us physical changes changes and their classification physical changes

The melting point of cadmium bromide is $568^{\circ}C$. Which of the following equations best describes what occurs when cadmium bromide is heated to $568^{\circ}C$?

  1. $CdBr(s)\rightarrow CdBr(l)$
  2. $CdBr _{2}(s)\rightarrow CdBr _{2}(l)$
  3. $CdBr _{2}(s)\rightarrow Cd(s) + Br _{2}(g)$
  4. $CdBr _{2}(s) \rightarrow Cd^{2+} (aq) + 2Br^{-}(aq)$
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Melting point is defined as the temperature at which solid is converted to liquid.

Given, Melting point of $Cd{ Br } _{ 2 }={ 568 }^{ 0 }C$

So, At ${ 568 }^{ 0 }C$

${ CdBr } _{ 2 }\left( solid \right) \longrightarrow { CdBr } _{ 2 }\left( liquid \right) $
Ans :- A