Tag: change around us

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Questions Related to change around us

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

Which of the following is correctly matched?

  1. Making of ice cube - Physical Change.

  2. Folding of a paper - Chemical, Reversible.

  3. Breaking of a glass - Chemical, Irreversible.

  4. All of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Making an ice cube is a phase change from liquid to solid, which is a classic example of a physical change. The other options are incorrectly classified (e.g., folding paper is physical, breaking glass is physical).

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

Two changes are stated below:
(i.) A piece of magnesium gives of bright flames when burned.
(ii). A piece of iron glows red when heated strongly.
 Which of these is a physical change?

  1. Only i

  2. Only ii

  3. Both i and ii

  4. Neither i nor ii
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

When magnesium is burnt, it reacts with the heat and gives bright flames and this change cannot be reversed.
When iron heated strongly it turns red. When heating is stopped it cools and get backs to its original form. So this is a physical change.

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

Dissolving salt in water-is a/an:

  1. endothermic change

  2. exothermic change

  3. both A& B

  4. chemical combination
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When salt (solid crystal) is dissolved in water energy is required to break the intermolecular attraction between ions (Lattice energy). Hence the energy is collected from water which leads to a decrease in its temperature.

Hence endothermic reaction.

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

Pooja took a candle in a vessel and heated the vessel. Even though the candle did not burn, it changed its shape and state. What kind of change is this?

  1. Naturalization

  2. Physical change

  3. Chemical change

  4. None of these
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Candle is made up of wax which melts on heating.When candle kept in a vessel and heated, the wax melts. When candle is allowed to cool, the wax solidifies. No new substance is formed. So, this is a physical change.

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

In a physical change :

  1. new substances are not formed

  2. reaction is reversible

  3. change is temporary

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

Physical changes in a substance do not form new substances, these reactions are reversible and the change is temporary.

Physical changes are the changes affecting the form of a chemical substance, but not its chemical composition. They are used to separate mixtures into their component compounds, but cannot usually be used to separate compounds into chemical elements or simpler compounds.

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

Identify the substance that evaporates at room temperature.

  1. Water

  2. Oil

  3. Kerosene

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

Kerosene is more volatile than water and oil, meaning it evaporates more readily at room temperature due to weaker intermolecular forces between its molecules. While water does evaporate at room temperature (that's why puddles dry), kerosene has a higher vapor pressure and evaporation rate. Oil has the strongest intermolecular forces and evaporates very slowly. Ammonium chloride sublimates (solid to gas) rather than evaporates (liquid to gas).

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

In early winter mornings, we can see drops of water on the blades of grass. This is because of :

  1. photosynthesis

  2. transpiration

  3. condensation

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

Dew drops are formed due to condensation of water vapors. The air around us contains water vapors which we call moisture or humidity. Hot air contains more moisture as compared to cold air. During the night when the hot air comes into contact with some cold surface, water vapor present in it condenses on the cold surface in the form of droplets. These tiny drops of water are called dew drops.

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

Dissolution of carbon dioxide gas in water is  ________ change.

  1. chemical

  2. physical
  3. both of $A$ and $B$

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

Dissolution of carbon dioxide gas in water is both a physical and chemical change.
Carbon dioxide dissolves in water producing carbonic acid, also known as soda water.
$ CO _2 + H _2O\rightarrow H _2CO _3$
There will be an equilibrium constant that will dictate the relative concentration of dissolved gas to the corresponding acid that is formed.
Usually nonmetal oxides like$CO _2, SO _2, NO _2$  simply dissolve in water, depending on the partial pressure above the water, and Henrys law constant. This implies a physical change.