\n(iv) Increase in resistance with, die rise of temperature.<\/td>\n | Decrease in resistance with the rise of temperature.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Question 3:<\/strong> Differentiate between an Electrolytic cell and Electrochemical cell. \nAnswer:<\/strong><\/p>\n\n\n\nElectrolytic cell<\/strong><\/td>\nElectrochemical cell<\/strong><\/td>\n<\/tr>\n\nIt is a device (vessel) in which chemical changes are brought about with the help of electric energy.<\/td>\n | It is a device in which electric energy is generated as a result of chemical change.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Question 4:<\/strong> Differentiate between electrical conductivity of copper sulphate solution and copper metal. \nAnswer:<\/strong> Differences between electrical conductivity of copper sulphate solution and copper metal:<\/p>\n\n\n\nCopper sulphate solution<\/strong><\/td>\nCopper metal<\/strong><\/td>\n<\/tr>\n\nElectric current is by flow of ions.<\/td>\n | Electric current is by flow of electrons.<\/td>\n<\/tr>\n | \nIt is aqueous solution of ionic compound.<\/td>\n | It is a metal in solid state.<\/td>\n<\/tr>\n | \nCopper sulphate undergoes a chemical change.<\/td>\n | Copper metal remains unchanged chemically.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n Question 5:<\/strong> Choose A, B, C or D to match the descriptions (i) to (v) below. Some alphabets may be repeated. \nA. non-electrolyte \nB. strong electrolyte \nC. Weak electrolyte \nD. metallic conductor \n(i) Molten ionic compound \n(ii) Carbon tetrachloride \n(iii) An aluminium wire \n(iv) A solution containing solvent molcules, solute molecules and ions formed by the dissociation of solute molecules. \n(v) A sugar solution with sugar molecules and water molecules. \nAnswer:<\/strong> (i) B, (ii) A, (iii) D, (iv) C, (v) A.<\/p>\nQuestion 6:<\/strong> Give three differences between sodium atom and sodium ion. \nAnswer:<\/strong> (i) Sodium atom is neutral in nature, while sodium ion is a positively charged particle. \n(ii) Sodium atom vigorously reacts with water to liberate hydrogen gas, while sodium ion does not react with water. \n(iii) Sodium atom tends to lose an electron to form sodium ion with a complete octet in the outermost shell.<\/p>\nQuestion 7:<\/strong> Explain how electrolysis is an example of a redox reaction. \nAnswer:<\/strong> Redox reactions are called simultaneous oxidation-reduction reactions. In electrode reactions, the positively charged ions (cations) accept electrons from the cathode to form neutral atoms, i.e., at cathode reduction takes place. At the anode, the negatively charged ions (anions) lose electrons to form neutral atoms, i.e., anode oxidation takes place. So, electrode reactions also signify oxidation-reduction reactions. Hence, they are also called Redox reactions.<\/p>\n | | | | | | |