REVISION WORK

REVISION WORK

I.                   ONE MARK QUESTIONS;

1.     When a white powder was mixed with acetic acid a colourless gas produced

            which turns lime water milky. What is the white powder? 

2.     What are saturated hydrocarbons?

3.     Write the structural formula of any isomer of n-heptane? (C₇H₁₆)

4.     Define the term catenation.

II.                 TWO MARKS QUESTIONS:

1.     Give two limitations of Mendeleev’s periodic classification.

2.     How does valency vary in a period on going left to right and in going down a group?

3.     Give reason: why the atomic radii of elements increases in a group while moving from top to bottom?

4.     State Mendeleev’s periodic law. why could no fixed position be given to hydrogen in mendeleev’s periodic table?

5.     i. name the property of ethanol which makes it useful in medicines.

ii. name the organic compound used in pickles. Mention its composition.

III.              THREE MARKS QUESTIONS:

1.     Write molecular, electronic and structural formulae of ethane.

2.     A. How does valence electrons vary :

i)                   In a group        ii) in a period

b. why do all elements in a group have same chemical properties?

c . How does tendency to lose electrons vary along a period? Why?

3.     A.distinguish between esterification and saponification reactions of organic compound.

b. describe an activity to show the formation of an ester.

4. complete the following reactions:

     a. C₂H₅OH     +  CH₃COOH -----à

      b. R-C=C-R   + H₂----à

      c. CH₃COOC₂H₅     +  NaOH ----à

5. An organic acid ‘X’ is a liquid which often freezes during winter time in cold countries, has the molecular formula C₂H₄O₂ . on warming it with ethanol in the presence of few drops of con. H₂SO₄., a compound ‘Y’ with sweet smell is formed.

        i. identify ‘X’ and ‘Y’.

       ii. write a chemical equation for the reaction involved.

6.     i. an element has atomic number 12. Is it metal or non-metal, why?

ii. why do we classify elements?

iii. do isotopes have same or different places in modern periodic table? Give reasons.

IV.              FIVE MARKS QUESTIONS:

1.     A) what would be electron dot structure of a molecule of sulphur which is made up of eight atoms of sulphur?

b) draw electron dot structure of ethane.

          2.       a. draw all structural isomers of pentane.

    b. draw structure of Butanone and bromopentane.

          3.       give an example of each:

     a. a carbon compound containing two double bond.

     b. a molecule in which central atom is linked to three other atoms.

     c. a compound containing both ionic and covalent bond

      d. an organic compound soluble in water

      e. a carbon compound burns with a sooty flame.

 4. atomic number of few elements are given below:

                                10, 20, 7, 14

a.     Identify these elements

b.     Identify group number of these elements

c.      Period of the elements

d.     Electronic configuration of these elements

e.     Determine the valency of these elements

5. a. why does carbon form compounds mainly by covalent bonding?

             b. what if 5% solution of KMnO₄ is added drop by drop to warm ethanol                                taken in a test tube

  c. give a chemical test to distinguish ethanol from ethanoic acid.

6.       a. name the element with atomic number 12(.ans: Mg)

           b. name a metal in making cans and member of group 14. (ans: Tin)

           c. a lustrous non metal having 7 valence electrons.( ans; Iodine)

           d. highly reactive metal given violet colour to flame. ( ans: K)

           e. a gas used in coloured advertising lights having 2 valence electrons (Ne)

7.  Identify A to E in the following equations:

       a. CH₃CH₂OH -----àA      (in presence of KMnO₄  and KOH)

       b. CH₃CH₂OH   + A   --à  B  (in presence of con. H₂SO₄)

       c.  NaOH + B  ---à C + CH₃CH₂OH

       d. NaHCO₃       +  A ----à C  +  D   +    H₂O

       e. CH₃CH₂OH   +   E  ---à CH₃CH₂COONa      +  H₂

ANS: a. ethanoic acid    b. ethyl ethonoate  c. Sodium ethanoate d. CO₂   e. Na

      

8.a.  complete the following reactions:

        a. CH₃CH₂CH₂OH     +  2 [O]   --à        

        b. C₂H₅COOH    +  NaHCO₃ -----à

        c. C₃H₇COOC₂H₅    +  NaOH  ----à

       B. Write the names of the compound:

            a. CH₃CH₂COCH₃

             b. CH₃COOC₂H₅

ANS:          a. CH₃CH₂CH₂OH     +  2 [O]   --à   CH₃CH₂COOH   + H₂O    

        b. C₂H₅COOH    +  NaHCO₃ -----à C₂H₅COONa   + CO₂  +  H₂O    

        c. C₃H₇COOC₂H₅    +  NaOH  ----à C₃H₇COONa  + C₂H₅OH 

B .              a. CH₃CH₂COCH₃  - Butan -2-one

             b. CH₃COOC₂H₅    -   Ethyl Ethanoate

9. an organic compound ‘X’ on heating with con. Sulphuric acid, forms a compound ‘Y’ which on addition of one molecule of hydrogen in the presence of Ni forms a compound ‘Z’. One molecule of compound ‘Z’ on combustion forms two molecules of CO₂ and three molecules of H₂O. Identify ‘X’ , ‘Y’ and ‘Z’ and write the reactions involved.

ANS:   since 1 molecule of Z gives 2 molecule of CO₂ and 3 molecules of H₂O on combustion, it means Z has two carbon and its molecular formula is C₂H₆.

The compound Z is obtained by addition of 2 hydrogen to Y . therefore Y is C₂H₄. The compound Y is obtained by heating compound ‘X’ is with con. H₂SO₄., it means X is C₂H₅OH.

Refer NCERT book p.no. 72