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What are the pH values of distilled water and common salt solution
Which acid is present in sour milk or curd?
A dry pellet of a common base B, when kept in open absorbs moisture and turns sticky. The compound is also a by-product of chloralkali process. Identify B. What type of reaction occurs when B is treated with an acidic oxide? Write a balanced chemical equation for one such solution.
What is the difference between slaked lime and lime water?
For question two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.
Assertion: Higher the H+ ion concentration, lower is the pH value.
Reason: The pH of a neutral solution = 7, that of a basic solution< 7 and that of an acidic solution> 7.
.(a) A solution has a pH of 7. Explain how you would you:
(i) increase its pH
(ii) decrease its pH
(b) If a solution changes the colour of the litmus from red to blue, what can you say about its pH?
(c) What can you say about the pH of a solution that liberates carbon dioxide from sodium carbonate?
Write a balanced chemical equation for the reaction between sodium carbonate and hydrochloric acid indicating the physical state of the reactants and products.
A knife, which is used to cut a fruit, was immediately dipped into water containing drops of blue litmus solution. If the colour of the solution is changed to red, what inference can be drawn about the nature of the fruit and why?
A few drops of phenolphthalein indicator were added to an unknown solution A. It acquired pink colour. Now another unknown solution B was added to it dropwise and the solution ultimately became colourless. Predict the nature of the solutions A and B.
An old person complained of acute pain in the stomach. Doctor gave him a small antacid tablet and he got immediate relief. What actually happened?
The oxide of a metal M was water soluble. When a blue litmus strip was dipped in this solution, it did not undergo any change in colour. Predict the nature of the oxide.
Why is potassium iodide added into common salt to use it as table salt?
During summer season, a milkman usually adds a small amount of baking soda to fresh milk. Give reason.
For question two statements are given-one labelled Assertion (A) and the other labelled Reason (R). Select the correct answer to these questions from the codes (a), (b), (c) and (d) as given below:
(a) Both A and R are true, and R is correct explanation of the assertion.
(b) Both A and R are true, but R is not the correct explanation of the assertion.
(c) A is true, but R is false.
(d) A is false, but R is true.
Assertion: The process of dissolving an acid or a base in water is highly exothermic reaction.
Reason: Water must always be added slowly to acid with constant stirring.
Explain why:
(i) Common salt becomes sticky during the rainy season
(ii) Blue vitriol changes to white upon heating
(iii) If bottle full of concentrated sulphuric acid is left open in the atmosphere by accident, the acid starts flowing out of the bottle of its own.
How do H+ ions exist in water?
A milkman adds very small amount of baking soda to fresh milk. What happens to its pH?
Which bases are called alkalies? Give an example of an alkali.
How will you find pH of lemon juice?