32
Chemi
EXAM PRACTICE QUESTIONS
1. Very short answer type questions (1 mark each)
1. What is the physical nature of matter?
2. Give one example of diffusion.
3. What is the size of particles in matter as determined by the experiments?
4. Name two factors which influence the physical state of matter,
5. Arrange the three states of matter in the order of increasing intermolecular space.
6. How is ice changed into water and then into steam?
7. Name the property which is responsible for high compressibility of gases.
8. Name the commonly used unit of temperature. Express the melting point of ice on this scale of temperature.
9. Which of the two causes severe burns at the same temperature - steam or water?
10. Name the process responsible for cooling of water kept in an earthen pot.
11. Name a substance that is liquefied by changing both temperature and pressure.
12. Is vaporisation an exothermic or endothermic process?
13. Under what conditions, the relative humidity is 100%?
II. Short answer type questions (2 marks each)
14. How can you support the particulate nature of matter with the help of an experiment involving the diss
of sugar?
15. Show by a simple experiment that diffusion becomes faster when temperature is raised.
16. Define intermolecular force.
Answers
Answer:
1) The three states of matter are the three distinct physical forms that matter can take in most environments: solid, liquid, and gas. In extreme environments, other states may be present, such as plasma, Bose-Einstein condensates, and neutron stars.
2) Perfume is sprayed in one part of a room, yet soon it diffuses so that you can smell it everywhere. A drop of food coloring diffuses throughout the water in a glass so that, eventually, the entire glass will be colored. Water diffuses into cooking noodles, making them bigger and softer.
(1) Solid , liquid and gas
(2) The smell of perfume
(3)10^-9
(4) Temperature, pressure and intermolecular space
(5) Inter-molecular space is the space between two molecule or atom. In solids it is little, it is more in liquids is more the solids but less than liquids and in gases it's the maximum and so in order of increasing inter-molecular spaces we have solids, liquids and gases.
(6) If ice (a solid) is heated it changes to water (a liquid). This change is called MELTING. If water is heated, it changes to steam (a gas). This change is called BOILING.
(7) In gases the intermolecular force of attraction is very less. They have large intermolecular spaces so they are free to move in all direction and so they are very compressible.
(8) The Kelvin (K) is the SI unit of temperature. Temperature has a fixed starting pointcalled absolute zero, which is defined as zero kelvin (0 K) and is the equivalent of –273.15 °C (–459.76 °F).
(9) Steam
(10) The evaporation is responsible for cooling of water in the earthen pot.
(11) petrol or kerosene is liquified by changing both temperature and pressure and is converted to liquified petroleum gas(L P G).
(12) Endothermic process
(13) The condition is known as supersaturation. At any given temperature and air pressure, a specific maximum amount of water vapor in the air will produce a relative humidity(RH) of 100 percent. Supersaturated air literally contains more water vapor than is needed to cause saturation.
(14) Take water in a glass. Add a spoon of salt in the glass of water and stir. The salt will dissolve and the water will taste salty. The salt particles dissolve in water because they occupy the spaces between the particles of water in the glass.
(15) When you put food coloring in cold water, it takes longer for the molecules to mix with the water. But when you drop food coloring in hot water, diffusion occurs must faster, and easier.
(16) The force of attraction between the molecules of matter is called the intermolecular force of attraction. It is maximum in solids, less in liquid and least in gases.