Lakhmir Singh & Manjit Kaur Test: Matter in Our Surrounding - Class 9

At 100°C, water exists in both the liquid state as well as in gaseous state. This is special condition because 100°C is the boiling point of water and as well as liquefaction temperature of the water vapour

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.  Other common values are 293 K (20 C or 68 F). Evaporation is a surface phenomenon but boiling is bulk phenomenon. Liquid having low boiling points evaporate faster. Cooling is not caused during boiling.

Cooling is field due to evaporation of acetone. Acetone is a highly volatile material which means it evaporates too fast at normal temperature also and it process of evaporating it takes the latent heat from hand to change its state from liquid to gas that's why we feel cool when we apply acetone.

The correct option is C.
Zero on the Celsius scale (0°C) is the equivalent to 273.15K. 1-degree rise in Celsius scale is equivalent to the 1-degree rise in the Kelvin scale.
 Conversion Formula for the temperature is:C=K−273
300-273= 27 C

Particles of solids have a 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 the correct order of increasing attraction between particles is Oxygen, water and sugar.

Camphor, ammonium chloride and iodine are sublimable substance. 

Change of solid state into liquid state is known as Fusion. Change of liquid state into gaseous state is known as Vapourization. Change of  vapour state into liquid state is known as condensation. Change of liquid state into solid state is known as Solidification. 

Solid and liquid have fixed volumes but gas has no fixed volume it is because the particles of gas have large intermolecular space but very very low intermolecular forces and the particles of gases can move freely.

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

Evaporation of water increases 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 change of solid directly into vapours is called  Sublimation. The change of liquid state into vapours without coming to it's boiling point is called Evaporation. The latent heat of Vaporization is the heat required to change the state of 1 kg into vapours. Latent heat of fusion is the heat required to Change the state of 1 kg of solid  into liquid.

Gases have no definite shape and volume and are highly incompressible. solid poses rigidity and liquid and gases possess fluidity.

When the pressure on the surface of a gas is increased. The particles of gases come 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 the weather is hot and dry.

Boiling point of water 100^oC +273 = 373k 

Melting point of water 0^oC = 273 K

Boiling point of Acetone = At atmospheric pressure acetone has a boiling point of 56°C

Melting poitn of aluminium = 660.3 °C

Ether and Acetone is most volatile. Alcohol is moderately volatile and water is least volatile. So, the statement, Acetone is least volatile is an 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 are the same. So, statement A is correct but B is wrong.

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

On increasing temperature more number of particles get enough K.E. to go into the vapour sate. Humidity is the amount of water vapour present in air. When humidity of air is low, the rate of evaporation is high and water evaporates more readily. When humidity of air is high, the rate of evaporation is low and water evaporates very slowly.

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 particles 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 is called the 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 an aendothermic process.

The physical state of water at 10^°C is liquid state. Below 0^°C water is in solid state and above 100^°C water is in vapour state.

Matter is composed of very small particles called atoms, hence matter is not continuous but particulate in nature.