English Medium इयत्ता १० - CBSE Question Bank Solutions for Science

Look at below figure and answer the following questions.

1.  What change would you observe in the calcium hydroxide solution taken in tube B?
2. Write the reaction involved in test tubes A and B respectively.
3. If ethanol is given instead of ethanoic acid, would you expect the same change?
4. How can a solution of lime water be prepared in the laboratory?

How would you bring about the following conversions? Name the process and write the reaction involved.

What is the role of concentrated Sulphuric acid when it is heated with Ethanol at 443 K. Give the reaction involved.

Name the compound formed when ethanol is heated at 443 K in the presence of conc. \[\ce{H2SO4}\] and draw its electron dot structure.

State the role of conc. \[\ce{H2SO4}\] in the reaction.

What happens when ethanol is heated at 443K in the presence of conc. H₂SO₄? Write the role of conc. H₂SO₄ in this case.

Draw electron dot structure of Ethanol.

In an experiment to study the properties of ethanoic acid, a student takes about 3 mL of ethanoic acid in a dry test tube. He adds an equal amount of distilled water to it and shakes the test tube well. After some time he is likely to observe that

(A) a colloid is formed in the test tube.

(B) the ethanoic acid dissolves readily in water.

(C) the solution becomes light orange.

(D) water floats over the surface of ethanoic acid.

While studying saponification reaction, a student measures the temperature of the reaction mixture and also finds its nature using blue/red litmus paper. On the basis of his observations the correct conclusion would be

(A) the reaction is exothermic and the reaction mixture is acidic.

(B) the reaction is endothermic and the reaction mixture is acidic.

(C) the reaction is endothermic and the reaction mixture is basic.

(D) the reaction is exothermic and the reaction mixture is basic.

Write three different chemical reactions showing the conversion of ethanoic acid to sodium ethanoate. Write balanced chemical equation in each case. Write the name of the reactants and the products other ethanoic acid and sodium ethanoate in each case.

A student puts a drop of reaction mixture of a saponification reaction first a blue litmus paper and then on a red litmus paper. He may observe that:

(a) There is no change in the blue litmus paper and the red litmus paper turns white.

(b) There is no change in the red litmus paper and the blue litmus paper turns red.

(c) There is no change in the blue litmus paper and the red litmus paper turns blue.

(d) No change in colour is observed in both the litmus papers

For preparing soap in the laboratory we require an oil and a base. Which of the following combinations of an oil and a base would be best suited for the preparation of soap?

(a) Castor oil and calcium hydroxide

(b) Turpentine oil and sodium hydroxide

(c) Castor oil and sodium hydroxide

(d) Mustard oil and calcium hydroxide

A student adds a spoon full of powdered sodium hydrogen carbonate to a flask containing ethanoic acid. List two main observations, he must note in his note book, about the reaction that takes place. Also write chemical equation foe the reaction.

When ethanol reacts with ethanoic acid in the presence of conc. H₂SO₄, a substance with fruity smell is produced. Answer the following:-

(i) State the class of compounds to which the fruity smelling compounds belong. Write the chemical equation for the reaction and write the chemical name of the product formed.

(ii) State the role of conc. H₂SO₄ in the reaction.

Consider the following comments about saponification reactions:

I. Heat is evolved in these reactions.

II. For quick precipitation of soap, sodium chloride is added to the reaction mixtures.

III. Saponification reactions are a special kind of neutralisation reactions.

IV. Soaps are basic salts of long-chain fatty acids.

The correct comments are

(a) I, II and III

(b) II, III and IV

(c) I, II and IV

(d) Only I and IV

What do you observe when you drop a few drops of acetic acid to test tubes containing

(a) phenolphthalein

(b) distilled water

(c) universal indicator

(d) sodium hydrogen carbonate powder

A student adds 2 mL of acetic acid to a test tube containing 2 mL of distilled water. He then shakes the test tube well and leaves it to settle for some time. After about 5 minutes he observes that in the test tube there is :

(A) a clear transparent colourless solution

(B) a clear transparent pink solution

(C) a precipitate settling at the bottom of the test tube

(D) a layer of water the layer of acetic acid

When you add about 2 ml of acetic acid to a test tube containing an equal amount of distilled water and leave the test tube to settle after shaking its contents, what will you observe in the test tube after about 5 minutes?

(A) A white precipitate settling at its bottom

(B) A clear colourless solution

(C) A layer of water over the layer of acetic acid

(D) A layer of acetic acid over the layer of water