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Question 1.
You have been provided with three test tubes. One of them contains distilled water and the other two contain an acidic solution and a basic solution, respectively. If you are given only red litmus paper, how will you identify the contents of each test tube?
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Question 2.
Why should curd and sour substances not be kept in brass and copper vessels?
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Question 3.
Which gas is usually liberated when an acid reacts with a metal? Illustrate with an example. How will you test for the presence of this gas?
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Question 4.
Metal compound A reacts with dilute hydrochloric acid to produce effervescence. The gas evolved extinguishes a burning candle. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride.
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Question 5.
Why do HCl, HNO3, etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?
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Question 6.
Why does an aqueous solution of an acid conduct electricity?
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Question 7.
Why does dry HCl gas not change the colour of the dry litmus paper?
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Question 8.
While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?
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Question 9.
How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?
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Question 10.
How is the concentration of hydroxide ions (OH–) affected when excess base is dissolved in a solution of sodium hydroxide?
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Question 11.
You have two solutions, A and B. The pH of solution A is 6 and pH of solution B is 8. Which solution has more hydrogen ion concentration? Which of this is acidic and which one is basic?
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Question 12.
What effect does the concentration of H+(aq) ions have on the nature of the solution?
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Question 13.
Do basic solutions also have H+(aq) ions? If yes, then why are these basic?
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Question 14.
Under what soil condition do you think a farmer would treat the soil of his fields with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate)?
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Question 15.
What is the common name of the compound CaOCl2?
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Question 16.
Name the substance which on treatment with chlorine yields bleaching powder.
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Question 17.
Name the sodium compound which is used for softening hard water.
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Question 18.
What will happen if a solution of sodium hydrocarbonate is heated? Give the equation of the reaction involved.
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Question 19.
Write an equation to show the reaction between Plaster of Paris and water.
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