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

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.

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

Melting of wax is a _________ change.

  1. physical

  2. chemical
  3. both $A$ and $B$

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

No new substances are formed. In a burning candle, there are both physical and chemical changes. The melting of the solid wax to form liquid wax and the evaporation of liquid wax to form wax vapour are physical changes. The burning of the wax vapour is a chemical change.

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

In ___________ , the properties of molecules remain same even after the change.

  1. physical change

  2. chemical change

  3. biochemical change

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

A physical change is any change in matter that involves the substance going from one physical state to another. 

The reference to a physical state involves solids, liquids, and gases. When a substance undergoes a physical change it does not lose its original properties because no new formation takes place when changing from one phase to another. The types of physical changes can vary. A substance can go from a solid to a liquid, a liquid to a gas, a gas to a liquid, a liquid to a solid, a solid to a gas, or a gas to a solid.

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

An iron ball at $\displaystyle { 50 }^{ \circ  }C$ is dropped in a beaker of water at $\displaystyle { 50 }^{ \circ  }C$. The heat will 

  1. Not flow from iron ball to water

  2. Not not flow from iron ball to water or from water to iron ball

  3. Not flow from water to iron ball

  4. Increase the temperature of both
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Energy flows always from a higher temperature to lower temperature. In this case there is no temperature  difference hence energy would not flow in any way.