Class 9 Science
Question 11: A sample of water under study was found to boil at 102°C at normal temperature and pressure. Is the water pure? Will this water freeze at 0°C? Comment.
Answer: The boiling point of pure water is 1000C. Soluble impurities increase the boiling point of a liquid. As the sample of water boils at 1020C, hence it is not pure. Impurities does not affect the freezing point, hence the given sample of water will freeze at 00C.
Question 12: A student heats a beaker containing ice and water. He measures the temperature of the content of the beaker as a function of time. Which of the following (Fig. 1.1) would correctly represent the result? Justify your choice.
Answer: Figure (d) represents the result correctly.
Explanation: Initially temperature of the content of beaker does not rise, because of latent heat of fusion. When all ice melts and, the temperature of content starts rising, hence, figure (d) represents the result correctly.
Question 13: Fill in the blanks:
Answer: (a) Cooling (b) Stronger (c) liquid, gaseous (d) sublimation, liquid (e) evaporation
Question: -14 - Match the physical quantities given in column A to their S I units given in column B :
Column A | Column B |
---|---|
(1) Pressure | (a) Cubic meter |
(2) Temperature | (b) Kilogram |
(3) Density | (c) Pascal |
(4) Mass | (d) Kelvin |
(5) Volume | (e) Kilogram per cubic meter |
Answer: (1) c, (2) d, (3) e, (4) b, (5) a
Question 15: The non S I and S I units of some physical quantities are given in column A and column B respectively. Match the units belonging to the same physical quantity:
Column A | Column B |
---|---|
(1) Degree Celsius | (a) Kilogram |
(2) Centimeter | (b) Pascal |
(3) Gram per centimeter cube | (c) Meter |
(4) Bar | (d) Kelvin |
(5) Milligram | (e) Kilogram per meter cube |
Answer: (1) d, (2) c, (3) e, (4) b, (5) a
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