Matter In Our Surroundings - Compulsory Test (22-06-2017) - Class 9 MCQ

Water exists in all three physical state of matter. At 25⁰C physical state of matter is LIQUID.

An almirah is solid because it is hard and rigid, have fixed shape and have very high density. All these properties are possessed by solid substance only.

The normal room temperature is 298K or 25^∘C. Evaporation is a surface phenomenon but boiling is bulk phenomenon. Liquid having low boiling points evaporate faster. Cooling is not caused during boiling.

Evaporation causes cooling effect because heat of evaporation is absorbed by the surroundings. Evaporation of acetone present in nail polish remover cause cooling o nail.

Particles of solids have very high force of attraction, particles of liquid have less force of attraction than solids and particles of gases have very less force of attraction. So correct order of increasing attraction between particles is Oxygen, water and sugar.

The constant temperature at which solid start changing into liquid at atmospheric temperature is called melting point. At this temperature, both the solid and liquid exist together.

The correct matching between the given terms and their respective responses is:
(1) Fusion: Change of solid state into liquid state (4-C)
(2) Vaporization: Change of liquid state into gaseous state (1-A)
(3) Condensation: Change of vapor state into liquid state (3-C)
(4) Solidification: Change of liquid state into solid state (2-B)
So, the correct answer is option A: 1-D, 2-A, 3-C, 4-B.

According to ancient philosophers matter consists of five constituents (panchtatva). They are air, earth, fire, sky and water.

Solids substances have strongest inter-particle force of attraction. In the given substances, sodium chloride is solid, ethyl alcohol is liquid and ammonia and carbon dioxide are gases. So, the particles of Sodium bromide have strongest force of attraction.

Evaporation of water increase with increase in temperature, surface area and wind speed but decrease with increase in humidity. So, larger humidity will decrease the rate of evaporation.

The particles of gases are away from each other. So, gas has minimum inter particle force of attraction. Solids have maximum force of attraction.

When the pressure on the surface of a gas is increased. The particles of gases comes closer that increase the inter-particle force of attraction.

Desert cooler causes cooling effect due to evaporation of water as evaporation causes cooling effect. A desert cooler works more effectively when weather is hot and dry.

Explanation:
The correct match of the given terms is:
1. Inter mixing of substance on their own - Diffusion
2. Temperature at which liquid changes into vapor - Boiling point
3. Temperature at which solid changes into liquid - Melting point
4. Energy possessed by the particles of the matter - Kinetic energy
Detailed solution:
To match the given terms with their correct responses, we need to understand the definitions of each term:
1. Inter mixing of substance on their own - Diffusion: This refers to the process in which particles of different substances mix together and spread evenly without any external force. It occurs due to the random motion of particles.
2. Temperature at which liquid changes into vapor - Boiling point: This is the specific temperature at which a liquid changes into its gaseous state. At this temperature, the vapor pressure of the liquid is equal to the atmospheric pressure.
3. Temperature at which solid changes into liquid - Melting point: This is the specific temperature at which a solid substance changes into its liquid state. At this temperature, the solid particles gain enough energy to overcome the forces holding them together and start moving freely.
4. Energy possessed by the particles of the matter - Kinetic energy: This refers to the energy of motion possessed by the particles of matter. It depends on the temperature of the substance and is directly proportional to the speed of the particles.
Based on the above definitions, we can match the given terms with their correct responses:
- Inter mixing of substance on their own - Diffusion
- Temperature at which liquid changes into vapor - Boiling point
- Temperature at which solid changes into liquid - Melting point
- Energy possessed by the particles of the matter - Kinetic energy
Therefore, the correct match is option B: 1-A, 2-C, 3-B, 4-D.

Ether and Acetone is most volatile. Alcohol is moderately volatile and water is least volatile. So, the statement, Acetone is least volatile is incorrect statement.

Ether and Acetone is most volatile. Alcohol is moderately volatile and water is least volatile. So, the statement, Acetone is least volatile is incorrect statement.

A substance is said to be in liquid state if under normal pressure its melting point is below the room temperature. Melting point of solid and the freezing point of liquid is same. So, statement A is correct but B is wrong.

Alcohol is a volatile substance and when kept in china dish it start evaporating. Evaporation causes cooling effect. The method used to measure the temperature change in above observation is by using a thermometer.

To match the given substances with their correct boiling and melting points, we can use the following information:
Water:
- Boiling point of water is 100°C or 373K.
- Melting point of water is 0°C or 273K.
Acetone:
- Boiling point of acetone is 56°C.
- Melting point of acetone is -95°C.
Aluminum:
- Aluminum does not have a boiling point as it sublimes directly from a solid to a gas.
- Melting point of aluminum is 660°C.
Now, let's match the given substances with their correct boiling and melting points:
(1) Boiling point of water - 373K
(2) Melting point of water - 273K
(3) Boiling point of acetone - 56°C
(4) Melting point of aluminum - 660°C
Therefore, the correct match is:
- 1-C
- 2-B
- 3-D
- 4-A
Answer: A

Kelvin scale is used as standard unit of temperature. CO₂ is heavier gas than N₂ and O₂.

Gases have maximum fluidity and least rigidity. The particle of solids have negligible kinetic energy. Inter-particle attraction depends on the physical state of the matter. Potassium permanganate is purple in colour.

The chemical reaction in which heat is absorbed in called as endothermic reaction. The reaction in which heat is evolved is called exothermic reaction and the reaction in which no thermal changes occur is called a thermic process. Evaporation of ether occurs due to absorption of heat by surrounding. So, it is aendothermic process.

In the different sets of substance given above, salt, sugar and chalk are solid under ordinary temperature. As Mercury, water and oxygen and nitrogen are not solid.

Anything that occupies space and have mass is called matter. Inter-particle space is maximum in the gaseous state of substance. The particles constitute zig-zag path and solid is most compact state of substance. Matter is not always continuous in nature.