CBSE Guess > Papers > Important Questions > Class IX > 2009 > Science > Science By : Mr M. p. Keshri
CBSE CLASS I X
Matter In Our Sourroundings (Solved)
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Q. 91. Liquids generally have lower density as compared to solids. But you must have observed that ice floats on water. Find out why ?
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Q. 92. Show that the three states of matter are interchangeable.
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Q. 93. Three substances A, B and C melts at 0ºC, 56ºC and -140ºC, respectively and their boiling points are 100ºC, 158ºC and 15ºC. What will be the physical states of A, B and C at room temperature.
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Q. 94. When ice at -5ºC is heated, temperature increases to 0ºC and remains constant till the ice is changed to water. On further heating temperature again rises. Why ?
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Q. 95. Define latent heat of fusion and latent heat of vaporization.
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Q. 96. Explain the relation between boiling point of a liquid and intermolecular force of attraction between the particles of the liquid.
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Q. 97.Change the following temperature to Kelvin scale :
40ºC, 78ºC, 227ºC.
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Q. 98. At 80ºC, liquid benzene is in equilibrium with its vapours. Why particles of benzene vapours are more energetic than particles of liquid benzene?
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Q. 99. Why ice at 273 K is less energetic than water at the same temperature ?
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Q. 100. Define sublimation and give examples.
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Q. 101. Choose the substances from the following that shows the phenomenon of sublimation :
Ice, salt, ghee, coconut oil, ammonium chloride, naphthalene, camphor.
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Q. 102. Choose the substances which shows the process of sublimation :
Solid water, solid oxygen, solid carbon dioxide, solid alcohol.
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Q. 103. In winter, ghee freezes at room temperature and mustered oil does not. Which of these has a higher melting point and lower intermolecular force ?
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Q. 104. Explain the effect of temperature and pressure on a gas.
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Q. 105. Differentiate between a gas and a vapour.
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Q.106. Define pressure.
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Q. 107. What is atmospheric pressure ?
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Q. 108. Ice at 273 K is more effective than water at 273 K. Explain.
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Q. 109. Explain the effect of pressure on the boiling point of liquid.
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Q. 110. Convert the following temperature to Celsius scale.
(a) 300 K
(b) 573 K
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Q. 111. What is the physical state of water at ?
(a) 250ºC
(b) 100ºC
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Q. 112. For any substance, why does the temperature remain constant during the change of state ?
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Q. 113. Suggest a method to liquefy atmospheric gases.
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Q. 114. Liquids are converted both by boiling and evaporation. What is the basic difference between the two process ?
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Q. 115. Define the term evaporation.
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Q. 116. State and explain the factors affecting evaporation.
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Q. 117. Evaporation cause cooling of a liquid system. Why ?
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Q. 118. Wet clothes kept in shade dry slowly in a rainy day even in summer. Why ?
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Q.119. How does human body maintain its temperature during summer ?
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Q. 120. How will you show that evaporation increases with the increase in surface area ?
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Q. 121. How will you show that evaporation increases with the increase in wind speed ?
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Q. 122. Give reason for the following :
Solid carbon dioxide (dry ice) is kept under high pressure.
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Q. 123. Why after rain in summer, heat becomes unbearable ?
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Q. 124. How does the water kept in an earthen pot (matka or kalsi) become cool during summer ?
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Q. 125. Why are we able to sip hot tea or milk faster from a saucer rather than a cup ?
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Q. 126. What type of clothes should we wear in summer ?
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Q. 127. What is a plasma ?
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Q. 128. Does fluorescent tube contains plasma ?
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Q. 129. Why do the sun or the stars glow ?
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Q. 130. Do all particles or plasma glow in a similar way ?
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Q. 131. Differentiate between a gas and plasma.
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Q. 132. Convert the following temperature to the Celsius scale :
(a) 300 K
(b) 573 K
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Q. 133. Convert the following temperatures to Kelvin scale :
(a) 25ºC
(b) 373ºC
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Q. 134. Give reasons for the following observations.
(a) Naphthalene balls disappear with time without leaving any solid.
(b) We can get the smell of perfume sitting several metres away.
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Q. 135. Arrange the following substances in increasing order of forces of attraction between the particles – water, sugar, oxygen.
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Q. 136. What is the physical state of water at :
( a) 25ºC
(b) 0ºC
(c) 100ºC
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Q. 137. Give two reasons to justify :
(a) Water at room temperature is liquid.
(b) An iron almirah is a solid at room temperature.
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Q. 138. What produces more severe burns, boiling water or steam ?
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Paper By Mr. M. P. Keshari [ For Further Enquiry 09434150289]
