Science In Everyday Life Solutions for Class 8 Science Chapter 13 Chemical Effects Of Current are provided here with simple step-by-step explanations. These solutions for Chemical Effects Of Current are extremely popular among class 8 students for Science Chemical Effects Of Current Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the Science In Everyday Life Book of class 8 Science Chapter 13 are provided here for you for free. You will also love the ad-free experience on Meritnation’s Science In Everyday Life Solutions. All Science In Everyday Life Solutions for class 8 Science are prepared by experts and are 100% accurate.

Page No 184:

Question 1:

Why do impurities dissolved in water increase its conductivity?

Answer:

The addition of impurities results in the formation of ions which are electrically charged particles. The movement of these ions allows the flow of electric current in the solution, increasing its conductivity.

Page No 184:

Question 2:

When an electric current is passed in an electrolytic cell, how can we make out that electrolysis is taking place?

Answer:

We can say that electrolysis is taking place if we observe:

a. Formation of bubbles at the cathode indicating that gases are being produced (or)
b. Deposition of metal on the electrodes (or)
c. Colour change of the electrolyte.

Page No 184:

Question 3:

Name two metals that are widely used in the automobile industry for protection from corrosion of metal parts.

Answer:

Zinc and Cadmium are the two metals that are used in the automobile industry to protect the metal parts from corrosion.

Page No 184:

Question 4:

Name two metals used in electroplating for decoration purposes.

Answer:

Silver and gold are the two metals that are used in electroplating for decoration purposes.

Page No 184:

Question 5:

What is anode mud?

Answer:

In the process of electrorefining of metals, an impure metal is made the anode and the pure metal is made the cathode. On passing electric current, impure metal gets dissolved in the solution and pure metal gets deposited at the cathode. The insoluble impurities from the metal which settle down below the anode are together called anode mud.

Page No 184:

Question 1:

Give reasons for the following.
(a) Operating electrical appliances with wet hands is very dangerous.
(b) Sodium chloride solution is a good conductor of electricity.
(c) Pure water is a poor conductor of electricity.

Answer:

(a). Operating electrical appliances with wet hands is very dangerous as it may lead to electric shocks and even death. This is because water containing impurities is a good conductor of electricity. This makes wet skin several times more electrically conductive than dry skin. 
(b). Sodium chloride is a salt, which is a poor conductor of electricity in its solid phase. However, when the salt is dissolved in water, they form sodium and chloride ions. Ions are charged particles which accommodate the flow of electric current in the salt solution. Therefore, sodium chloride solution acts as a good conductor of electricity.
(c). Pure water is a poor conductor of electricity because it has very few ions in it to conduct electricity. 

Page No 184:

Question 1:

Define/Explain the following.
1. Electrical conductivity
2. Ions
3. Electrolyte
4. Electrolysis
5. Electroplating
6. Electrorefining

Answer:

  1. Electrical conductivity: The measure of the ability of a material to accommodate the flow of an electric charge is called electrical conductivity.
  2. Ions:  Ions are a group of atoms that carry a net electric charge.
  3. Electrolyte: A liquid containing ions which acts as a medium to conduct electricity is called an electrolyte.
  4. Electrolysis: The method of producing a chemical reaction by supplying electric current through liquids containing ions is called electrolysis.
  5. Electroplating:  A process which uses electric current to coat one metal with another.
  6. Electrorefining: The process of removing impurities from a metal using electrolysis is called electrorefining.

Page No 184:

Question 1:

Which of these is a good conductor of electricity?
(a) Pure water
(b) Wood
(c) Sodium chloride solution
(d) Rubber

Answer:

(c) Sodium chloride solution

Sodium chloride solution is a good conductor of electricity.

Page No 184:

Question 2:

Anions are attracted to the
(a) cathode
(b) anode
(c) electrolyte
(d) walls of the container

Answer:

​(b) anode
​Anions are negatively charged ions which are attracted to the anode which is electrically positive.

Page No 184:

Question 3:

Most acids and bases dissolved in water are
(a) good conductors of electricity
(b) poor conductors of electricity
(c) good insulators
(d) contain very few ions

Answer:

(a) Good conductors of electricity
Most of the acids and bases when dissolved in water act as fairly good conductors of electricity.

Page No 184:

Question 4:

Electrolysis of a solution of sodium chloride produces
(a) hydrogen gas at the cathode
(b) chlorine gas at the anode
(c) sodium hydroxide
(d) all of these

Answer:

(d) All of these

Electrolysis of a solution of sodium chloride produces hydrogen gas at the cathode, chlorine gas at the anode and sodium hydroxide.

Page No 184:

Question 5:

In electrorefining of metals, the impure metal is taken as
(a) the anode
(b) the cathode
(c) either anode or cathode
(d) the electrolyte

Answer:

(a) the anode

The impure metal is taken as the anode in the process of electrorefining of metals.

Page No 184:

Question 1:

Fill in the blanks with the correct words.
1. Alcohol is a .................... (good/bad) conductor of electricity.
2. Dilute solutions of acids .................... (can/cannot) be used as electrolytes.
3. Positively charged ions are called .................... (anions/cations).
4. Anode mud gets .................... .................... (deposited on/collected below) the anode.
5. The process of .................... (electroplating/electrorefining) can be used to purify metals.

Answer:

  1. Alcohol is a bad conductor of electricity.
  2. Dilute solutions of acids can be used as electrolytes.
  3. Positively charged ions are called cations.
  4. Anode mud gets collected below the anode.
  5. The process of electrorefining can be used to purify metals.



Page No 185:

Question 2:

Describe two uses of electrolysis.

Answer:

Electrolysis is the production of a chemical reaction by passing an electric current to liquid containing ions. The two uses of electrolysis are :
(a). Used in the industry in the production of many metals such as aluminium and magnesium.
(b). Used in the removal of impurities from metals such as gold and silver through a process known as electrorefining.

Page No 185:

Question 3:

Describe electroplating with examples.

Answer:

Electroplating is a method which uses electrolysis to deposit a layer of one metal on another metal. The object to be coated is made the cathode and the metal to be deposited is made the anode. On the application of electric current, the metals in the ionic form move from the anode and get deposited as a layer on the cathode object.

Examples:  

  1. Zinc and chromium are commonly used metals in plating steel and iron in order to protect from corrosion, wear and rust to the metal. 
  2. Gold metal is used to electroplate metals like copper or silver for ornamental or decorative purposes.

Page No 185:

Question 4:

With respect to electrorefining of copper, answer the following questions.
(a) which object is used as the anode?
(b) Name the electrolyte used.
(c) What is used as the cathode?

Answer:

In electrorefining copper:

  1. Impure copper rod is taken as the anode
  2. Copper Sulphate solution is the electrolyte
  3. A thin strip of pure copper is taken as the cathode.



View NCERT Solutions for all chapters of Class 8