# Class 9 Science CBSE worksheet for matter in our Surroundings

Given below are the Class 9 Science CBSE Important questions for matter in our Surroundings
a) Very Short questions
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Question 1. What is condensation? How is the condensation of a gas carried out?

Question 2. Why do solids not diffuse?

Question 3. Convert the following Kelvin temperature to degrees Celsius.
a. 175 K
b. 295 K
c. 300 K
d. 225 K

Question 4. Convert the following Celsius temperature to Kelvin temperature.
a. 25 0C
b. -15 0C
c. 0 0C
d. 3 0C

Question 5. Arrange the following substances in increasing order of intermolecular force of attraction:
water, sugar, oxygen

Question 6.  What is the physical state of water at the following temperatures?
(a) 25 0C
(b) 0 0C
(c) 100 0C

Question 7. Why does the temperature of a substance remain constant during melting and boiling even when heat is being supplied to it continuously?
Question 8. Explain the diffusion of copper sulphate into water.
Question 9. A constant pressure tank of gas at 1.01 Atm has propane in it at 150C when it is at 255 cubic meters. What is its volume at 480C?

Question 10. What is the mass of 15 liters of chlorine gas at STP?

Question 11. How many liters of hydrogen at 00C and 1400mm of Hg are produced if 15g of magnesium reacts with sulphuric acid?

Question 12. A 250 Kg tank of liquid butane (C4H10) burns to produce carbon dioxide at 1200C. What volume of carbon dioxide is produced at 1 Atm?

Question 13. How many liters of product at 950 mmHg and 00C is produced by the burning of three liters of acetylene (C2H2) at 5 atm and 200C?

Question 14. A fixed quantity of gas at 230C exhibits pressure of 748 torr and occupies a volume of 10.3 L
a)Use Boyle's law to calculate the volume the gas will occupy at 230C if the pressure is increased to 1.88 atm.
b)Use Charles' law to calculate the volume the gas will occupy if the temperature is increased to 1650C while the pressure is held constant.

Question 15. (a) Write the ideal- gas equat ion, and give the units used for each term in the equation when
Given that R = 0.0821 L-atm/mol- K
(b) What is an ideal gas?

Question 16. A certain volume of a gas is under a pressure of 900 mm of Hg. When the pressure is increased by 300 mm, the gas occupies 2700 ml. if this change occurs at a constant temperature, calculate the initial volume of the gas.
Question 17. Which state of matter is compressible? Why?

Question 18. Why do the gases exert more pressure on the walls of the container than the solids?

Question 19. The process in which a solid is converted directly into a gas is called sublimation. Iodine is an element that sublimes. A sample of solid iodine in a stoppered flask was allowed to stand undisturbed for several days. Crystals of solid iodine grew on the sides of the flask. Explain at the molecular level what happened?
Question 20. At a pressure of 2 atmosphere a fixed mass of hydrogen occupies a volume of 8 liters. What pressure must be maintained if the volume is to be increased to 10 liters, temperature remaining constant?
Question 21. A given mass of a gas occupies 960 ml at 270C C. What volume will it occupy if the temperature is raised to 1770C C, pressure remaining constant?
Question 22. Give three examples of crystalline and amorphous solids.

Question 23. Why is motor oil more viscous than water? Does motor oil have a greater surface tension than water.
Question 24. Describe why a drop of food coloring in a glass of water slowly becomes evenly distributed without the need for stirring?
Question 25. Liquid mix more slowly than gases. Why?
Question 26. Define the following terms:
a. Melting point
b. Freezing point
c. Boiling point