Last updated on February 9th, 2024 at 04:31 pm
CG Board Class 8 Science Chemical Effects of Electric Current Textbook Exercises which includes Fill in the blanks ,Question Answers and Extra Question and Answers from the Chapter.
1. Tick the correct answer –
(i) Which of the following is not a good conductor of electricity –
(a) Distilled Water[answer]
(b) lemon Juice
(c) Salty Water
(d) Tap Water
(ii) The electrolyte used in a simple voltaic cell is –
(a) Dilute sulphuric acid[answer]
(b) Dilute hydrochloric acid
(c) Copper sulphate solution
(d) Potassium hydroxide solution.
(iii) The process of depositing a layer of any desired metal on another material by means of electricity is known as –
(a) Electrolysis
(b) Electroplating[answer]
(c) Chemical reaction
(d) Electro refining
(iv) The apparatus used for electrolysis is –
(a) Electric cell
(b) Voltameter[answer]
(c) Ammeter
(d) Magnetic needle
2. Fill in the blanks –
(i) Solution of …………………………………. electrolyte is used in simple voltaic cell.[copper sulphate]
(ii) On passing current through any solution, produces……………………. effect.[chemical]
(iii) In solar cell …………… energy is converted into …………………………… energy.[solar , electrical]
(iv) Process of coating of expensive metals over cheap metals by voltaic cell is called…………..[electroplating]
(v) …………… cells are used in watches, calculator, transistors and artificial satellites.[Button]
ANSWER THESE
Q. What do you mean by good and poor conductor of electricity?
Good conductors of electricity allow electric current to flow through them easily, while poor conductors hinder the flow of electric current.
Q. Why distilled water is poor conductor while tap water is good conductor of electricity?
Distilled water is a poor conductor because it lacks dissolved ions, whereas tap water contains dissolved salts and minerals, making it a good conductor.
Q. What do you mean by chemical effect of electric Current?
The chemical effect of electric current refers to the chemical reactions that occur when an electric current passes through a conducting solution, leading to changes such as gas bubble formation, metal deposition, or changes in solution color.
Q. What are the main reasons of doing electroplating?
Electroplating is done to coat one metal with another, for purposes like corrosion resistance, aesthetics, and improving conductivity.
Q. Name some electroplated objects available in your surrounding by making a list.
Objects that are commonly electroplated include jewelry, silverware, car parts, kitchen faucets, and bicycle handlebars.
Q. Which electrode and electrolyte is used in a simple voltaic cell?
In a simple voltaic cell, the anode is made of zinc and the cathode is made of copper. The electrolyte is typically a solution of dilute sulfuric acid.
Q. What is a solar cell made of?
A solar cell is made of two layers of silicon, with one layer doped with boron and the other with arsenic. These layers create a positive and a negative region, allowing them to generate electricity from sunlight.
Q. Does distilled water conduct electricity? If not what can we do to make it a conductor?
Distilled water is a poor conductor of electricity due to lack of ions. Adding a soluble ionic compound, such as table salt (sodium chloride), to water that dissociates into ions can make it a conductor.
Q. In case of fire, before the fireman uses the water they shut off the main electrical supply for the area. Explain why they do this?
Firefighters turn off the main power supply during a fire to avoid electrical shock. Water is a good electrical conductor, and spilling it on electrical equipment or exposed wires can create dangerous conditions, which can cause electric shock or other hazards.
Q. Why zinc is coated with iron?
Zinc is often coated with iron in a process known as galvanization. This is done to protect the underlying zinc from corrosion.
Q. Explain the process of electrolysis?
Electrolysis is a chemical process in which Negative ions move to the negative electrode (cathode) and positive ions move to the positive electrode (anode). This causes chemical decomposition of the electrolyte and new substances are formed.
Q. Name the electrolyte, positive terminal and negative terminal of button cell.
In a button cell, the electrolyte is typically sodium or potassium oxide. The positive terminal is made of silver oxide or mercury oxide, and the negative terminal is typically made of zinc.
Q. Write 3 uses of electroplating.
Three uses of electroplating are:
- Enhancing the appearance of items, such as gold or silver jewellery, by giving them a shiny and attractive metallic finish.
- Coating steel with a more corrosion-resistant metal to protect it from galvanization.
- Creating a conductive surface on non-metallic materials such as plastics or ceramics for printed circuit boards or electronic components.
