Chap-7 Electro chemistry

 

 

Objective Part

Choose the right option.                                                               10×1=10

A

B

C

D

1

Which one of the following is not an electrolytic cell

Downs cell

Galvanic cell

Nelson’s cell

Both a and c

2

The oxidation number of chromium in K2Cr2O7 is:

+2

+6

+7

+14

3

The formula of rust is:

Fe2O3.nH2O

Fe2O3

Fe(OH)3.nH2O

Fe(OH)3

4

Electrolysis of NaCl is done in the cell

Electrolytic

Voltaic

Downs

Faraday’s

5

In dry cell _____ act as cathode:

Zn cup

Graphite rod

Paste

Steel rode

6

An example of weak electrolyte is:

Glucose

Aq. NaCl

HCl

H2SO4

7

Cations are ______ ions.

Positive

Negative

Neutral

None of these

8

The most common example of corrosion is:

Chemical decay

Rusting of iron

Rusting of aluminium

Rusting of tin

9

Spontaneous chemical reactions take place in:

Electrolytic cell

Galvanic cell

Nelson’s cell

Downs cell

10

In redox reaction between Zn and HCl, the oxidizing agent is:

Zn

H+

Cl-

H2

 

 

 

                                                                                    Total Marks= 25

Name______________                             Class: 9th                                            Subject: Chemistry

Subjective

Answer the short questions.                                                                               10×2=20

1.      Differentiate between oxidizing and reducing agents.

2.      Why O2 is necessary for rusting?

3.      Differentiate between strong and weak electrolyte.

4.      Why galvanizing is done?

5.      Define corrosion.

6.      Where does the sodium metal is collected in Downs cell?

7.      Which type of chemical reaction takes place in electrolytic cell?

8.      What is the difference between valency and oxidation state?

9.      Name the by-products produced in Nelson’s cell.

10.  Define oxidation-reduction or redox reaction.

 

Long Questions                                                                 5×1=5

1.      (a) What is electroplating? How electroplating of chromium is carried out?                    3

(b) Write down the rules for assigning oxidation state or oxidation number.                   2