[CDATA[ Under what soil condition do you think a farmer would treat the soil of his fields with quick lime (calcium oxide) or slaked lime (calcium hydroxide) or chalk (calcium carbonate)? 3. Water is less dissociated into H+ and OH– ion. It is aqueous solution of ionic compound. Electricity is conducted with the help of free sodium and chloride ions, which are present in fused sodium chloride. 1 point is earned for a correct explanation. Some alphabets may be repeated. //]]>. conduct electricity. (iv) Lead ions and bromide ions are present in pure lead bromide in molten state. Why does an aqueous solution of an acid conduct electricity? (ii) Water acidified with sulphuric acid between platinum electrodes. Buffers resist change in pH in a system when. window.__mirage2 = {petok:"cd40cc3e15034a006ee4547848acf4f64efa43ec-1614683445-1800"}; Equal lengths of magnesium ribbons are taken in test tubes A and B. Hydrochloric acid (HCl) is added to test tube A, while acetic acid (CH. (ii) Name the ions present in the cell. Plaster of Paris should be stored in a moisture-proof container. Answer: Molten lead bromide (PbBr2) forms and Br– ions. Concentrated hydrochloric acid being strong electrolyte gets fully dissociated furnishing H+ and Cl– ion. Answer: Question 3: Differentiate between an Electrolytic cell and Electrochemical cell. (2) Electro-refining of Metals. Answer: (i) Molecules are present in a non-electrolyte. Write a balanced chemical equation for the reaction if one of the compounds formed is calcium chloride. 13. Answer: Differences between electrical conductivity of copper sulphate solution and copper metal: Question 5: Choose A, B, C or D to match the descriptions (i) to (v) below. A solution reacts with crushed egg-shells to give a gas that turns lime-water milky. the strength of above acids come down to the level of H 3 O + strength in water. Hence, sugar solution is bad conductor of electricity. But mercury is a metal, so on dissolving in water, it can’t break up into cations and anions, When electric current passes through mercury it doesn’t undergo any decomposition and no new substance is formed. The hydroxide ion turns red litmus paper blue. 9. Why? In electrode reactions, the positively charged ions (cations) accept electrons from cathode to form neutral atoms, i.e., at cathode reduction’takes place. 4. It is because, the blue colour of electrolyte is due to the presence of Cu2+ ions. Answer: (i) Nickel sulphate (ii) Key chain (iii) Pure nickel plate (iv) Ni2+ + 2e–  ⟶   Ni (v) Ni – 2e–   ⟶   Ni2+. 6. Which solution is. Hence, sugar solution is bad conductor of electricity. As Cu2+ ions discharge at cathode, therefore their concentration in electrolyte decreases. Download Formulae Handbook For ICSE Class 9 and 10. Acids, Bases and Salts Notes of CBSE Class 10 Science Chapter with detailed explanation of the chapter ‘Acids, bases and salts' along with meanings of difficult words. As the electrolysis is . Thus, H2 gas would be discharged at cathode 2H+ + 2e–   ⟶   2H   ⟶   H2 Later, as the solution turns blue due to formation of Cu++ ions, the Cu++ ions will get discharged to 2H+ ions as they are less electropositive Cu2+ + 2e–   ⟶   Cu↓. Answer: (i) X – 2e–   ⟶   X2+ Y + 3e–   ⟶   Y3- (ii) 3X+2 + 2Y-3   ⟶   X3Y2 (iii) (1) Electroplating of Metals. You have two solutions, A and B. Copper sulphate undergoes a chemical change. Examples of polar solvents are water, methanol, and formamide. conducts electricity when dissolved in water, but does not conduct electricity in the solid phase. Give two examples. (ix) Why the electrolytic solution acidified. Since H 3 O + is the strongest acid in water. Question 17: The following questions refer to the electrolysis of copper sulphate solution with copper electrodes. Similarly when salt is dissolved in water, it ionizes to form ions. Nanomaterial adsorbents (NAs) have emerged as efficient candidates to remove toxic metals from water. Answer: (i) Mass of Cathode increases where as that of anode decreases due to deposition of pure copper on cathode. (iv) Write the equations of the reaction which take place at the cathode and anode. 4. Adsorption is widely applied in both potable and municipal or industrial wastewater treatments process. (ii) The conductivity of metals is due to movement of electrons. (iv) Direct current is used to get smooth coating and the phase of the current is same at all instance of time. 4. When electric current is passed through silver nitrate solution, electrolysis takes place and silver is deposited as a fine thin film at the surface of spoon. Why? Question 23. (vii) If electric current is passed for a very long time, state colour change taking place in electrolyte. 2. Acidified nickel sulphate solution with nickel electrode. 1. (iii) No change in chemical properties of the conductor. Question 21: Mention the type of ions present, the products obtained and the electrode reactions that occur, when the following are electrolysed : (i) Molten lead bromide between steel cathode and graphite anode. Pure water does not conduct electricity. Arrange the pH in increasing order of hydrogen-ion concentration. 11. Common salt which we use daily in our food is a strong electrolyte. Thus concentration of copper ions goes on decreasing. The sulphuric acid just helps in increasing the conductivity of water. In Cell B: Acetic acid being weak electrolyte ionises only partially and therefore, only a weak current flows. Explain why? Hence, solution of sodium chloride is good conductor of electricity. 12.A milkman adds a very small amount of baking soda to fresh milk. Now, it behaves like a stronger electrolyte and hence the bulb glows brightly. Question 6: A solution of ionic compound is an electrolyte, while that of covalent compound is non electrolyte? M + M   ⟶  M2 (v) Oxygen gas is liberated at anode. (a) Why does he shift the pH of the fresh milk from 6 to slightly alkaline? State one reason for the change. (ii) Write the equation representing the reaction that occurs. Why ? (vi) Write the reaction at the cathode. (b) Give the equation for the discharge of ions at the cathode. not a not c. ... Strong acids Weak acids Weak bases Strong bases HBr CH3COOH NH3 NaOH HNO3 HF NH4OH KOH … Answer: Dilute acids produce a large number of hydronium ions, so they behave like strong electrolytes. Answer: (i) At cathode red shiny metal deposits. The pH of rain water collected from two cities A and B was found to be 6 and 5 respectively. Distilled water does not conduct electricity because it does not contain any ionic compound (like acids, bases or salts) dissolved in it. Label three plastic cups or Mason jars #1–3 using a permanent marker. Thus concentration of copper ions in electrolyte remain unchanged. (vi) 4OH– – 4e–   ⟶   2H2O + O2 (g) (vii) The electrolyte gets decolourised. In the above context answer the following: (i) What kind of combination exists between M and O ? Lewis acid is a chemical … Question 12: How will you electrolyse the molten solution of lead bromide? (ix) Name the gas liberated at cathode after the colour changes in electrolyte. (iii) Why crucible is heated from outside ? (iii) The crucible is heated from outside to keep lead bromide in the molten sate. Thus, solution of ionic compound is good conductor of electricity and hence is electrolyte. e fuel cells system weighs above . (ii) Why a small current passed for a longer period is preferred over high current for a shorter period ? Therefore due to absence of free ions, wax does not conduct electricity. (ix) To increase the electrical conductivity of electrolyte. Electroplating a spoon with silver. Thus, gradually blue colour fades away. (iv) The ions migrating towards the cathode is Cu2+. 1. Yanghui Li, Lei Wang*, Shi Shen, Tao Liu, Jiafei Zhao, and ; Xiang Sun* Illustrate with an example. (iii) The article to be electroplated is always placed at cathode because the metal is always deposited at cathode. How does the addition of sulphuric acid produce a conducting solution? Question 24: Element X is a metal with a valency 2. NaCl (aq) Na + + Cl-Hence salts can also conduct electricity. (i) Draw a labelled diagram of the electrolytic cell. In water, the ammonia molecules react with water and ionise to produce ammonium ions and hydroxide ions. (d) dilute hydrochloric acid reacts with iron filings. (ii) How many electrons are there in the outermost shell of M ? Decrease in resistance with the rise of temperature. Solutions of Ionic Compounds. State the most likely place for the metal in electrochemical series. (iv) What particles are present in pure lead bromide? NCERT Solutions For Class 10 Science 2020-2021 - NCERT Solutions for Class 10 Science helps the students to practice as many question papers and improve their knowledge on the subject present in the NCERT Class 10 Science 2020-2021 Text Book as per the NCERT(CBSE). Answer: It is because the amount of sulphuric acid does not change when water is electrolysed. Study the diagram given below and answer the question that follows: (i) Which electrode to your left or right is known as the oxidising electrode and why ? Write an equation to show the reaction between Plaster of Paris and water. Silver wire and a spoon, which is to be plated with silver, are dipped in the solution. Question 8: (i) Write equations to show the electrolytic dissociation of: (a) Two acids (b) Two bases. (v) Overall strength of silver ions does not change in the electrolyte as the number of Ag+ ions entering the electrolyte is equal to the number of Ag+ ions discharged at cathode. (iii) Write two applications of electrolysis in which the anode diminishes in mass. Name the sodium compound which is used for softening hard water. In Cell C: Sugar being a covalent compound does not ionise at all and therefore, no current flows. Acids Bases and Salts Class 10, Summary, Explanation and Notes of Acids Bases and Salts Science Chapter 2 . The gas evolved extinguishes a burning candle. Question 25: Mr. Ramu wants to electroplate his key chain with nickel to prevent rusting. Hence, it is non-electrolyte. Answer The presence of hydrogen (H +) or hydronium (H 3 O +) ions in the aqueous solution of an acid are responsible for conducting electricity… Answer: (i) (a) Acids: H2SO4   ⇌   2H+ + SO42- HNO3   ⇌   H+ + NO3– (b) Bases: NaOH    ⇌    Na+ + OH– KOH    ⇌    K+ + OH– (ii) When electricity is passed through fused sodium chloride, the electrolysis starts as follows : NaCl    ⇌    Na+ + Cl– Na+ + e–   ⟶   Na (At cathode) Cl– – e–  ⟶   Cl Cl + Cl   ⟶  Cl2 (At anode) Sodium metal is deposited at cathode, while chlorine gas is liberated at anode. A solution turns red litmus blue, its pH is likely to be, 2. (iv) If the compound formed between X and Y is melted and an electric current passed through the molten compound, the element X will be obtained at the … and Y at the … of the electrolytic cell. (viii) In such a situation the copper atoms on copper anode ionise and enter into electrolyte. Answer: Strong electrolytes —Ammonium chloride, dilute hydrochloric acid, dilute sulphuric acid. (iii) The electrolysis of copper sulphate solution is used in the purification of copper using pure copper plate as cathode and impure copper plate as anode. Some indicator compounds can be used to detect acids, such as litmus. (y) The overall strength of silver ions remain constant in the reaction. Answer: The blue colour of electrolyte is due to the presence of copper ions in it. Given here is the complete explanation of the chapter, … 18.37 g of sodium chloride dissolved in 92.2 g of water. What is a neutralization reaction? 5. Answer: (i) Sodium atom is neutral in nature, while sodium ion is a positively charged particle. (vii) Write the reaction at the anode. Question 3: (i) Study the diagram given below and answer the questions that follows : (a) Give the names of the electrodes A and B. Academia.edu is a platform for academics to share research papers. (iii) Name the ions migrating towards the anode. Similarly.strong bases like NaOH. Thus, only electricity is suitable as reducing agent which provides unlimited amount of energy to break ionic bonds easily. Answer: During electrolysis of aqueous copper sulphate using copper electrodes, the two anions OH–.and S042- migrate to the anode, but none of them get discharged because the copper of the anode dissolves in the solution producing copper ions and electrons. //