Tag: physical changes

Questions Related to physical changes

A mixture of sand and salt can be separated by:

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

  1. Sublimation

  2. Sieving

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

  4. Dissolving salt in water and then distillation

Show answer
Correct Option: D
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.

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

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

  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

Show answer
Correct Option: C
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.

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

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

  1. Chromatography

  2. Precipitation

  3. Filtering

  4. Distillation

Show answer
Correct Option: C
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.

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

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

  1. Physical change

  2. Chemical change

  3. Both physical and chemical changes

  4. None

Show answer
Correct Option: A
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.

Melting of butter is a physical change.

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

  1. True

  2. False

Show answer
Correct Option: A
Explanation:

Yes, melting of butter is a physical change because the butter can be solidified again (i.e. reversible change).

In melting of butter only state of the chemical substance is changed.

Boiling water is a _____ change because _____.

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

  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

Show answer
Correct Option: A
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.

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 $868^{\circ}C$?

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

  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. $CdBr _{2}(s)\rightarrow Cd^{2+}(aq) + 2Br^{-}(aq)$

Show answer
Correct Option: A

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

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

  1. A physical change

  2. A chemical change

  3. Both a physical and a chemical change

  4. A permanent change

Show answer
Correct Option: A
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.

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?

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

  1. A physical reaction

  2. A chemical reaction

  3. An exothermic reaction

  4. An endothermic Reaction

Show answer
Correct Option: A
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

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 $568^{\circ}C$?

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

  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. $CdBr _{2}(s) \rightarrow Cd^{2+} (aq) + 2Br^{-}(aq)$

Show answer
Correct Option: B
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