Very Short Answer Questions
- Blue and red litmus papers are placed simultaneously in a colourless aqueous solution. It is found that the colour of both litmus papers is red. What is the nature of the solution and why?
- A strip of absolutely clear cloth is sprayed with onion juice. The strip is then rubbed with few drops of hydrochloric acid. Will the strip smell like onion? Give a reason for your answer
- Name two metals which react with concentrated sodium hydroxide solution to liberate hydrogen gas.
- Write the general word equation for reaction between acids and bases.
- Name an alkali solution which has no metallic ion.
- What is the pH of a neutral solution?
- What is a universal indicator?
- What do you understand by the term salt?
- Write fully balanced equation when carbon dioxide is passed through ammonical brine solution.
- Name a carbonate of a metal which has cleansing properties.
- Name the chemical which is used as a preservative in pickles and curing fish.
- Write the name and chemical formula of the products formed by heating gypsum
at 373 K.
- The pH of a sample of vegetable soup was found to be 6.5. How is this soup likely to taste?
- Write the names and chemical formula of the products formed by the action of chlorine on slaked lime.
- Write the name and chemical formula of the main product formed by heating baking soda.
- Which one is a stronger acid, with pH = 5 or with pH = 2?
- A compound which is prepared from gypsum has the property of hardening when mixed with proper quantity of water. Identify the compound and write its chemical formula.
- Name the acid present in ant sting.
- Name a salt which does not contain water of crystallisation.
- Why is it advised not to use copper or brass vessels to store pickles or curd?
- What happens when water is added to quick lime?
- Which bases are called alkalises? Give an example of an alkali.
- What would be the colour of litmus in a solution of sodium carbonate?
- Why does tooth decay start when the pH of the mouth is lower than 5.5?
- Which one of these has a higher concentration of H+ ions?
1 M HCl or 1 M CH3COOH
- What effect does an increase in concentration of H+(aq) in a solution have on the pH of the solution?
- Name the gas usually liberated when a dilute acid reacts with a metal. What happens when a burning candle is brought near this gas?
- Name the gas evolved when dilute HCl reacts with sodium hydrogen carbonate. How is it recognized?
- How will you test for a gas which is liberated when hydrochloric acid reacts with an active metal?
- On adding dilute hydrochloric acid to copper oxide powder, the solution formed is blue-green. Predict the new compound formed which imparts blue-green colour to the solution.
- How does the flow of acid rain into a river make the survival of aquatic life in the river difficult?
- How is the pH of a solution of an acid influenced when it is diluted?
- How does the pH of the solution change when a solution of a base is diluted?
- What is the role of acid in our stomach?
- Dry ammonia gas has no action on litmus paper, but a solution of ammonia in water turns red litmus paper blue. Why is it so?
- Write chemical equations to show the reactions taking place when a glass rod dipped in concentrated hydrochloric acid is introduced in a jar containing ammonia gas.
- Write the name and the chemical formula of the organic acid present in vinegar.
- Write balanced chemical equation for the reaction taking place when dry blue crystals of copper sulphate are dropped into concentrated sulphuric acid.
- Which will be more acidic and why?
(i) A solution with pH value of 6.0 or
(ii) A solution with pH value of 5.0.
SHORT ANSWER QUESTIONS
- Why does nitric acid not produce hydrogen, when treated with metals?
- Metal hydroxides and metal oxides are called bases. Explain and support your answer by balanced chemical equations.
- What happens when nitric acid is added to an egg shell?
- Give two examples of : (i) soluble bases (ii) partially soluble bases (iii) insoluble bases.
- Arrange the following solutions in order of decreasing H+(aq) ions concentration.
(i) ammonium hydroxide (ii) gastric juice (iii) vinegar (iv) sodium hydroxide
- Why does a bee sting cause pain and itching? What is the common remedy to overcome such a pain?
- Do basic solutions also have H+(aq) ions? If yes, then why are these basic?
- Two solutions R and Q are tested with universal indicator. The solution P turns red, whereas solution Q turns orange. Which solution : (i) is more acidic; (ii) has more pH.
- Name the acid present in ant sting and give its chemical formula. Also give the common method to get relief from the discomfort caused by the ant sting.
- How would you distinguish between baking powder and washing soda by heating?
- A sulphate salt of Group 2 element of the Periodic Table is a white, soft substance, which can be moulded into different shapes by making its dough. When this compound is left in open for some time, it becomes a solid mass and cannot be used for moulding purposes. Identify the sulphate salt and why does it show such a behaviour? Give the reaction involved.
- A substance ‘X’ is used for white washing.
(i) Name ‘X’ and write its formula
(ii) Write reaction of substance ‘X’ with water
- What is the colour of FeSO4.7H2O crystals? How does this colour change upon heating? Give balanced chemical equation for the changes.
- Classify the following salts into acidic, basic and neutral.
Potassium sulphate, ammonium chloride, sodium carbonate, sodium chloride.
- For making cake, baking powder is taken. If at home your mother uses baking soda instead of baking powder in cake.
(a) How will it affect the taste of the cake and why?
(b) How can baking soda be converted into baking powder?
- In one of the industrial processes used for manufacture of sodium hydroxide, a gas X is formed as by product. The gas X reacts with dry slaked lime to give a compound Y which is used as a bleaching agent in chemical industry. Identify X and Y.
- How washing soda is prepared from baking soda. Write balanced chemical equation. Give two uses of washing soda.
- What is amphoteric oxides? Give two examples of amphoteric oxide with balanced chemical equation.
- Name two salts that are used in black and white photography. Give reactions when they are exposed to light.
- While constructing a house, a builder selects marble flooring and marble table tops for the kitchen where vinegar and juices of lemon, tamarind, etc. are more often used for cooking. Will you agree to this selection and why?
- 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 person is suffering from indigestion due to the intake of hot spicy food. What remedy you will prescribe to the patient? Give the name of a chemical that can give relief to him.
- A white powder A is a mild non corrosive base and is used in the preparation of cakes. When the powder is heated it gives another powder B. The powder B is re-crystallised to get a substance C which has detergent properties. Identify A, B and C and also write balanced chemical equations for the conversions of A to B.
- When a drop of orange juice is added to pure water, how the pH value vary for water? If a drop of lemon juice is also added, will there be any more change in the pH value?
- Fresh milk has a pH of 6. How do you think the pH will change as it turns in to curd? Explain?
- A milkman added a small amount of baking soda of fresh milk.
(a) Why does he shifted the pH of fresh milk to slightly alkaline?
(b) Why does this milk take a longer time to set as a curd?
- HCl and HNO3 show acidic characters in aqueous solution while alcohol and glucose solution do not. Give reasons.
- Write the chemical formula for bleaching powder. How is bleaching powder prepared? For what purpose is it used in paper factories?
- Write the name and chemical formula of the calcium compound used for disinfecting drinking water. How is this compound manufactured?
- A compound which is prepared from gypsum has the property of hardening when mixed with a proper quantity of water. Identify the compound. Write the chemical equation for its preparation. For what purpose is it used in hospitals?
- What is ‘Baking Powder’? How does it make cakes soft and spongy?
- How is Plaster of Paris obtained? What reaction is involved in the setting of a paste of Plaster of Paris?
- (i) An aqueous solution has a pH value of 7.0. Is this solution acidic, basic or neutral?
(ii) Which has a higher pH value, 1 M HCl or 1 M NaOH solution?
- Given below are the pH values of four different liquids: 7.0, 14.0, 4.0, 2.0. Which of these could be that of
(i) lemon juice
(ii) distilled water
(iii) 1 m sodium hydroxide solution
(iv) tomato juice
- A calcium compound which is a yellowish white powder is used as a disinfectant and also in the textile industry. Name the compound. Which gas is released when this compound is left exposed to air?
- Name the gas evolved when dilute sulphuric acid acts on sodium carbonate. Write the chemical equation for the reaction involved.
- “Sulphuric acid is a dibasic acid.” Write two reaction equations to justify this statement and name the reaction products in the two cases.
- What happens when crystals of washing soda are left open in dry air? What is this change named as? Name two industries based on the use of washing soda.
- How is Plaster of Paris chemically different from gypsum? How may they be interconverted? Write one use of Plaster of Paris.