Chapter 2 - Acids, Bases and Salts
Chapter 3 - Metals and Non-metals
Chapter 4 - Carbon and its Compounds
Chapter 5 - Periodic Classification of Elements
Chapter 6 - Life Processes
Chapter 7 - Control and Coordination
Chapter 8 - How do Organisms Reproduce
Chapter 9 - Heredity and Evolution
Chapter 10 - Light - Reflection and Refraction
Chapter 11 - Human Eye and Colourful World
Chapter 12 - Electricity
Chapter 13 - Magnetic Effects of Electric Current
Chapter 14 - Sources of Energy
Chapter 15 - Our Environment
Chapter 16 - Management of Natural Resources
Chapter 2 - Acids, Bases and Salts
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?
Why should curd and sour substances not be kept in brass and copper vessels?
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.
Why do HCl, HNO3, etc., show acidic characters in aqueous solutions while solutions of compounds like alcohol and glucose do not show acidic character?
Why does an aqueous solution of an acid conduct electricity?
Why does dry HCl gas not change the colour of the dry litmus paper?
While diluting an acid, why is it recommended that the acid should be added to water and not water to the acid?
How is the concentration of hydronium ions (H3O+) affected when a solution of an acid is diluted?
How is the concentration of hydroxide ions (OH−) affected when excess base is dissolved in a solution of sodium hydroxide?
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?
What effect does the concentration of H+ (aq) ions have on the nature of the solution?
Do basic solutions also have H+ (aq) ions? If yes, then why are these basic?
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)?
What is the common name of the compound CaOCl2?
Name the substance which on treatment with chlorine yields bleaching powder?
Name the sodium compound which is used for softening hard water
What will happen if a solution of sodium hydrocarbonate is heated? Give the equation of the reaction involved.
Write an equation to show the reaction between Plaster of Paris and water
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A solution turns red litmus blue, its pH is likely to be
A solution reacts with crushed egg-shells to give a gas that turns lime-water milky. The solution contains
10 mL of a solution of NaOH is found to be completely neutralised by 8 mL of a given solution of HCl. If we take 20 mL of the same solution of NaOH, the amount of HCl solution (the same solution as before) required to neutralise it will be
(a) 4 mL
(c) 12 mL
(d) 16 mL
Which one of the following types of medicines is used for treating indigestion?
Write word equations and then balanced equations for the reaction taking place when dilute sulphuric acid reacts with zinc granules
Write word equations and then balanced equations for the reaction taking place when − dilute hydrochloric acid reacts with magnesium ribbon.
Write word equations and then balanced equations for the reaction taking place when dilute sulphuric acid reacts with aluminium powder
Compounds such as alcohols and glucose also contain hydrogen but are not categorized as acids. Describe an activity to prove it.
Why does distilled water not conduct electricity, whereas rain water does?
Why do acids not show acidic behaviour in the absence of water?
Five solutions A, B, C, D and E when tested with universal indicator showed pH as 4, 1, 11, 7 and 9, respectively. Which solution is
(b) strongly alkaline?
(c) strongly acidic?
(d) weakly acidic?
(e) weakly alkaline?
Arrange the pH in increasing order of hydrogen-ion concentration.
Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCl) is added to test tube A, while acetic acid (CH3COOH) is added to test tube B. In which test tube will the fizzing occur more vigorously and why?
Fresh milk from cows have pH of 6. So how does the pH change when this milk is turned to curd?
A milkman adds a very small amount of baking soda to fresh milk.
(a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline?
(b) Why does this milk take a long time to set as curd?
Plaster of Paris should be stored in a moisture-proof container. Explain why?
What is a neutralization reaction? Give two examples.
Give two important uses of washing soda
Give two important uses of baking soda.
When acids react with metal, which gas is liberated?