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

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.

Factors Affecting Rate of Evaporation

• Wind Speed: Higher wind speeds can increase the rate of evaporation by carrying away the water vapor molecules from the surface, creating a lower concentration of water vapor around the liquid. This allows more water molecules to evaporate.

• Surface Area: A larger surface area can increase the rate of evaporation as more liquid molecules are exposed to the air, allowing for more evaporation to occur.

• Temperature: Higher temperatures can increase the rate of evaporation as the kinetic energy of the liquid molecules increases, leading to more molecules escaping into the air.

• Insoluble Heavy Impurities: Insoluble heavy impurities do not affect the rate of evaporation. These impurities remain in the liquid and do not impact the evaporation process. The rate of evaporation is primarily influenced by factors such as wind speed, surface area, and temperature.

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.

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.

Melting point is defined as the temperature at which a solid turns into a liquid under atmospheric pressure.

In solids, particles are closely packed (very little space between them) and have the least kinetic energy.

In liquids, particles have moderate spacing and intermediate kinetic energy.

In gases, particles are far apart and move very rapidly, having the most kinetic energy.

Answer: B) The spaces between the particles and the kinetic energy are minimum in solids, intermediate in liquids, and maximum in gases.

The latent heat of vaporisation is the heat needed to convert 1 kg of a liquid into its gaseous state at the boiling point without increasing the temperature of the liquid.

Kelvin scale is used as standard unit of temperature. CO₂ (liquid state) is is stored under high pressure.

- Statement A: Potassium permanganate is actually purple in color, not orange. It is a powerful oxidizing agent commonly used in chemistry experiments.
- Statement B: Gases have maximum fluidity and least rigidity compared to liquids and solids. This is due to the fact that gas particles are far apart and move freely in all directions.
- Statement C: Solids do have a significant kinetic energy of particles, although it is less than that of liquids and gases. The particles in solids vibrate in fixed positions, contributing to their overall kinetic energy.
- Statement D: Inter-particle attraction does depend on the physical state of matter. In solids, the particles are closely packed together, leading to strong intermolecular forces. In liquids, the particles are more spread out, resulting in weaker forces. In gases, the particles are far apart and have very weak intermolecular forces.

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.