English Medium Class 10 - CBSE Question Bank Solutions for Science

Esters are sweet-smelling substances and are used in making perfumes. Describe an activity for the preparation of an ester with the help of a well labelled diagram. Write an equation for the chemical reaction involved in the formation of the ester. Also write the names of all the substances involved in the process of esterification.

Vinegar is a solution of about:
(a) 5 to 8 per cent ethanoic acid in alcohol
(b) 5 to 8 per cent ethanoic acid in water
(c) 50 to 80 per cent ethanoic acid in water
(d) 50 to 80 per cent ethanoic acid in alcohol

The substance which can produce brisk effervescence with baking soda solution is:
(a) ethanol
(b) vegetable oil
(c) vinegar
(d) soap solution(b) hydrocarbon ends directed towards the centre and ionic ends directed outwards
In a soap micelle, the soap molecules are arranged radially with the hydrocarbon ends, i.e. hydrophobic, directed towards the centre; and, ionic ends, i.e. hydrophilic, directed outwards.

Which of the following molecular formula corresponds to ethylbutanoate ester?
(a) C₅H₁₀O₂
(b) C₆H₁₂O₂
(c) C₇H₁₄O₂
(d) C₈H₁₆O₂

Consider the following organic compounds:
HCHO, C₂H₅OH, C₂H₆, CH₃COOH, C₂H₅CI
Choose two compounds which can react in the presence of conc. H₂SO₄ to form an ester. Give the name and formula of the ester formed.

A neutral organic compound is warmed with some ethanoic acid and a little of conc. H₂SO₄. Vapours having sweet smell (fruity smell) are evolved. What type of functional group is present in this organic compound?

The structural formula of an ester is :

Consider the following organic compound:
CH₃OH, C₂H₅OH, CH₃COCH₃, CH₃COOH, C₂H₅COOH, C₄H₉COOC₂H₅, CH₄, C₂H₆, CH₃CHO, HCHO
Out of these compound:

Which compound is most likely to be sweet-smelling?

 Consider the following organic compound:
CH₃OH, C₂H₅OH, CH₃COCH₃, CH₃COOH, C₂H₅COOH, C₄H₉COOC₂H₅, CH₄, C₂H₆, CH₃CHO, HCHO
Out of these compound:

Which compound is added to alcohol to denature it?

Consider the following organic compound:
CH₃OH, C₂H₅OH, CH₃COCH₃, CH₃COOH, C₂H₅COOH, C₄H₉COOC₂H₅, CH₄, C₂H₆, CH₃CHO, HCHO
Out of these compound:

Which compound is a constituent of vinegar?(e) Which compound is a constituent of vinegar?

An organic acid X is a liquid, which often freezes during winter time in cold countries, having the molecular formula C₂H₄O₂. On warming it with methanol in the presence of a few drops of concentrated sulphuric acid, a compound Y with a sweet  smell is formed.
(a) Identify X and Y. Also write their formulae showing the functional group present in them.
(b) Write a chemical equation for the reaction involved.

An organic compound A (molecular formula C₂H₄O₂) reacts with Na metal to form a compound B and evolves a gas which burns with a pop sound. Compound A on treatment with an alcohol C in the presence of a little of concentrated sulphuric acid forms a sweet-smelling compound D (molecular formula C₃H₆O₂). Compound D on treatment with NaOH solution gives back B and C. Identify A, B, C and 

If you are asked to report your observations about the following two properties of acetic acid, what would you report?
(i) Odour
(ii) Effect on litmus

If you take a pinch of sodium hydrogen carbonate powder in a test-tube and add drop-by-drop acetic acid to it, what would you observe immediately? List any two main observations.

A student is studying the properties of acetic acid in his school laboratory. List two physical and two chemical properties which he must observe and note in his record book.

A student puts a drop of acetic acid first on a blue litmus paper and then on a red litmus paper. He would observe that
(A) the red litmus paper turns colourless and there is no change in the blue litmus paper.
(B) the red litmus paper turns blue and the blue litmus paper turns red.
(C) there is no change in the red litmus paper and the blue litmus paper turns red.
(D) there is no change in the blue litmus paper and the red litmus paper turns blue.

While studying saponification reactions, the following comments were noted down by the students :
(I) Soap is a salt of fatty acids.
(II) The reaction mixture is basic in nature.
(III) In this reaction heat is absorbed.
(IV) This reaction is not a neutralisation reaction.
Which of these are the correct comments ?
(A) I and III only
(B) I, II and III
(C) II, III and IV
(D) I and II only

A student is studying the properties of acetic acid. List two physical properties of acetic acid he observes. What happens when he adds a pinch of sodium hydrogen carbonate to this acid? Write any two observations.