Description : Why an electrolyte in molten or fused state is electrically neutral?
Last Answer : Ans: Because the number of + ve charges and –ve charges are equal , so as a result an electrolyte appears to be neutral in nature.
Description : What is modern theory about the existence of the ionic compounds in solid state?
Last Answer : Ans: According to modern theory these exist in form of ions even in solid state for example, sodium chloride exist as Na+ Cl- . Whereas according to the ionic theory it exists as NaCl.
Description : Ionic non polar solid dielectrics contain more than one type of atoms but no permanent dipoles. State True/False a) True b) False
Last Answer : a) True
Description : (a) Show the formation of Na2O by the transfer of electrons between the combining atoms. (b) Why are ionic compounds usually hard? (c) How is it that ionic compounds in the solid state do not conduct electricity but they do so when in molten state? -Chemistry
Last Answer : (b) It is due to strong force of attraction between oppositely charged ions. (c) In solid state, ions are not free to move whereas in molten state ions are free to move, therefore, they conduct electricity in molten state.
Description : Why gold ,silver and pt are used in making ornaments?
Last Answer : Ans: Because these are nobel metals and therefore their rusting doesn,t occure and also these are very lustorous(shiny),so due to these qualities ,these are used for making ornaments.
Description : Why for chromium plating iron is firstly platted by copper or nickel?
Last Answer : Ans: Because chromium metal doesn’t adhere directly to the iron properly so it is firstly plated with nickel or copper.
Description : What is electroplating and what is its objective?
Last Answer : Ans:The process in which one metal is deposited at other electrolytically. It is very useful process and following are objective of electroplating. (a) Deposition of Nobel metals on inferior metals. (b) Protection of different metals from corrosion. (c) Repair of broken machinery.
Description : How could we prevent H+ ions to be discharged first than Na+ during electrolysis of aqueous solution of NaCl?
Last Answer : Ans: This could be prevented by using mercury cathode during this kind of electrolysis, because H+ ions need high voltage to be discharged at mercury cathode. In this way sodium got discharged at cathode despite H+ ions.
Description : During electrolysis of aqeous solution of NaCl, there are two type of anions are present Cl- and –OH, Cl- is discharged first than –OH,although it is present below Cl- in electrochemical series. Give reason.
Last Answer : Ans: During this electrolysis process Chloride ions come from NaCl, which is a strong electrolyte and ionize to large extent so concentration of chloride ions in solution will be high. ... chloride ions it is first discharged despite of its presence above than hydroxyl in electrochemical series.
Description : Why cation present below in electrochemical series can discharge before the elements present above them in an electrochemical cell?
Last Answer : Ans: This is because their ability to be reduced (reduction potential) is more than the cation present above them in electrochemical series. So they take electrons before the other cations and get discharged.
Description : Why sulphuric acid is added to the water during electrolysis of water?
Last Answer : Ans: It is added to increase conduction of the water, because water is a weak electrolyte.
Description : In Down’s cell, why the reaction between sodium metal and chlorine gas must be avoided? And how could we prevent reaction between them?
Last Answer : Ans:In Down’s cell electrolysis of fused NaCl yields sodium metal and chlorine gas .If these are not separated these will react to form Nacl again. So to prevent these reaction in Down’s cell, we place a steel gauze between cathode and anode.
Description : Why carbon electrode is used during electrolysis of Nacl, instead of Pt electrode?
Last Answer : Ans: During electrolysis of Nacl, chlorine gas is produced at anode. Thus to avoid it’s reaction with platinum we use carbon electrode.
Description : What is “redox” reaction?
Last Answer : Ans: “The reaction in which both reduction and oxidation takes place is called redox reaction. Reduction: “Addition of electron in an atom”. Oxidation: “Removal of electron from an atom”.
Description : What is difference between electrolytic and voltaic cell?
Last Answer : Ans:In electrolytic cell a non-spontaneous redox reaction is carried out with help of electrical energy. Wherease In voltaic cell a spontaneous redox reaction generates the electrical energy.
Description : In a magnetic material, always there exist magnetic dipoles as well as monopoles. State True/False. a) True b) False
Last Answer : b) False
Description : In a static magnetic field only magnetic dipoles exist. State True/False. a) True b) False
Description : Give reason for the following: (a) Aluminium oxide is considered as an amphoteric oxide. (b) Ionic compounds conduct electricity in molten state. -Chemistry
Last Answer : a) Aluminium oxide reacts with both acids as well as bases.b) Ionic compounds in molten state conduct electricity. Explanation: a) An amphoteric oxide as one that shows chemical reactivity with ... ions are present in the liquid state. These free ions enable the solution to conduct electricity.
Description : Which of the following RP technologies uses molten material as the starting material? a.Three-Dimensional Printing b.Fused-Deposition Modeling c.Stereolithography d.Selective Laser Sintering
Last Answer : c.Stereolithography
Description : Which of the following is not used as a medium for high temperature heating ? (A) Dowtherm (B) Mercury (C) Liquid metal (e.g. molten sodium) (D) Fused salts (e.g., an eutectic mixture of 53% KNO3 , 40% NaNO2and 7% NaNO3 )
Last Answer : (B) Mercury
Description : Some substances are good conductor of electricity in both the solid and liquid states. These substances are generally-------? A. ionic substances B. metallic substances (Answer) C. molecular solids D. covalent network solids
Last Answer : B. metallic substances (Answer)
Description : Most covalent compounds (a) Behave like electrolytes in the molten state (b) Have high melting and boiling points (c) Are hard substances because of strong covalent bonds (d) Are more soluble in non-polar solvents than in polar solvents
Last Answer : Ans:(d)
Description : Give reason for the following observation (L-III) (a)- The tendency for catenation decreases down the group in group 14 (b)- The decreasing stability of+3 oxidation state with increasing atomic no. in group 13. (c)- Molten aluminum bromide is a poor conductor of electricity.
Last Answer : Ans. -(a) it is due to decrease in bond dissociation energy which is due to increase in atomic size C-C > Si-Si >Ge-Ge>Sn-Sn>Pb-Pb. (b)- It is due to inert pair effect. (c)- Molten AlBr3 is poor conductor of electricity because it is covalent compound.
Description : Which one of the following RP technologies uses solid sheet stock as the starting material? a.Droplet deposition manufacturing b.Fused-deposition modeling c.Laminated-Object Manufacturing d.Selective Laser Sintering
Last Answer : c.Laminated-Object Manufacturing
Description : Which of the following is not Solid-based RP system? a.Laminated Object Manufacturing (LOM) b.Paper Lamination Technology (PLT) c.Electron Beam Melting (EBM) d.Fused Deposition Modeling (FDM)
Last Answer : c.Electron Beam Melting (EBM)
Description : The metal A is prepared by the electrolysis of fused chloride. It reacts with hydrogen to form a colourless solid from which hydrogen is released on t
Last Answer : The metal A is prepared by the electrolysis of fused chloride. It reacts with hydrogen to form a colourless solid from ... is A. Al B. Ca C. Cu D. Zn
Description : Reaction between X and Y forms compound Z. X loses electron and Y gains electron. Which of the following properties is not shown by Z? A) Has high melting point B) Has low melting point C) Conducts electricity in molten state D) Occurs as solid
Last Answer : B) Has low melting point
Description : Pick out the wrong statement. (A) Cp of monatomic gases such as metallic vapor is about 5 kcal/kg.atom (B) The heat capacity of solid inorganic substance is exactly equal to the ... isolated system (D) At absolute zero temperature, the heat capacity for many pure crystalline substances is zero
Last Answer : (C) There is an increase in entropy, when a spontaneous change occurs in an isolated system
Description : (a) Show on a diagram the transfer of electrons between the atoms in the formation of MgO. Write symbols of cation and anion present in MgO. (b) Name the solvent in which ionic compounds are generally soluble. (c) Why are aqueous solutions of ionic compounds able to conduct electricity? -Chemistry
Last Answer : (b) Ionic compounds are soluble in water. (c) It is because aqueous solutions consist of ions which can move freely in them and carry current.
Description : Why do metals conduct electricity but crystals of ionic compounds do not conduct electricity ?
Last Answer : Metals have free electrons. These electrons, created to gain the electromagnetic positivity and octal structure of the metal, flow from the negative side of the electric source to the positive edge ... electrons does not occur in it. Therefore crystals of ionic compounds do not conduct electricity.
Description : Organic compounds are - (1) Covalent compounds (2) Ionic compounds (3) Co-ordination compounds (4) Interstitial compounds
Last Answer : (1) Covalent compounds Explanation: Organic compounds are always covalent compounds because it is more energetically favorable for carbon to covalently bond. Organic compounds, such as carbohydrates, lipids, proteins and nucleic acids, are all examples of covalent compounds.
Description : Give reason .the compounds of alkaline earth metals are less ionic than alkali metals
Last Answer : Ans This is due to increased nuclear charge and smaller size.
Description : From the elements: Cl, Br, F, O, Al, C, Li, Cs and Xe; choose the following: (a) The element with highest negative electron gain enthalpy. (b) The element with lowest ionization enthalpy. ( ... . (f)The element which belongs to zero group. (g) The elements which forms largest number of compounds.
Last Answer : Ans. (a). The element chlorine (Cl) has the highest negative electron gain enthalpy. (b). The element cesium (Cs) has lowest ionization enthalpy. (c). The element fluorine F has lowest atomic radius. (d ... zero group (or group 18). (g). The element carbon (C) forms the largest number of compounds.
Description : Which of the following is not a characteristic of organic compounds? (a) They usually have low melting points. (b) They usually are only slightly soluble or insoluble in water. (c) If water ... they seldom conduct an electric current. (d) Bonds which bind the atoms together are nearly always ionic.
Last Answer : Bonds which bind the atoms together are nearly always ionic.
Description : Define characteristic of Ionic & covalent compounds.
Last Answer : Characteristics Of Ionic Compounds : Physical State : Ionic compounds are solids at room temperature. In crystals the oppositely charged ions are mutually surrounded by each other in orderly ... tetrachloride. Inter Molecular Forces : They have weak intermolecular forces between bonded atoms.
Description : Why ionic compounds are more soluble in water than others?
Last Answer : Ans: As water is a polar compound, so it dissolves ionic compounds in large amounts due to its strong interaction with ions (solute particles).
Last Answer : This is due to increased nuclear charge and smaller size.
Description : Which one of the following statements concerning elements in the Periodic Table is correct? A Elements of the same group all have the same number of electrons in the outermost occupied electron shell. B ... (Group 17) are all gases at room temperature. E The Group 13 elements are all metals.
Last Answer : D) Are compounds that exhibit both metallic & non-metallic properties to some extent and are exemplified by elements like germanium, silicon & boron
Description : Which of the following four compounds would have t most ionic bond? w) CH4 x) LiF y) CsF z) N2
Last Answer : ANSWER: Y -- CsF
Description : Organic compounds are (1) Covalent compounds (2) Ionic compounds (3) Co-ordination compounds (4) Interstitial compounds
Last Answer : Covalent compounds
Description : Which of the following substances is an ionic netw solid? w) Diamond x) Table Salt y) Brass z) Dry ice
Last Answer : ANSWER: X -- TABLE SALT
Description : A net ionic equation does NOT show: w) electronic charges x) solid products (precipitates) y) spectator ions z) reacting species
Last Answer : ANSWER: Y -- SPECTATOR IONS
Description : Why can sodium fluoride conduct electricity when it is molten but not solid?
Last Answer : In solution or when is melted sodium fluoride is dissociated in ions.
Description : Sodium sulphur battery is a type of molten-salt battery constructed from _____ sodium and sulphur. • Solid • Liquid • Plasma • Gases
Last Answer : • Liquid
Description : Metalloids (A) Are good conductor of heat & electricity (B) Act as electron donors with metals & as electron acceptor with non metals (C) Are not necessarily solids at room temperature ... & non-metallic properties to some extent and are exemplified by elements like germanium, silicon & boron
Description : Assertion:- Ionic compounds exhibits electrical conductivity in solution state. Reason :- In solution state electrons of ionic compounds are free.
Last Answer : Assertion:- Ionic compounds exhibits electrical conductivity in solution state. Reason :- In solution state ... . If both Assertion & Reason are false
Description : State as to why: (a) A solution of Na2CO3 is alkaline? (b)alkali metals are prepared by electrolysis of their fused chlorides ? (c)sodium is found to be more useful than potassium ?
Last Answer : Ans. (a) It undergoes hydrolysis to produce a strong base NaOH . (b) When the aq. Solution of any alkali metal is subjected to electrolysis ,H2 instead of the alkali metal is produced at the ... of sugars and amino acids into the cells. Thus, sodium is found to be more useful than potassium.
Description : In winter an iron pipe feel colder than a wooden window . This is because wood is----? A. Conductor B. Non-Conductor (Answer) C. Semi- Conductor D. Not a solid while iron is a solid E. None of these
Last Answer : B. Non-Conductor (Answer)
Description : Why ionic crystals don't conduct electricity in the solid state?
Last Answer : In the solid state ionic crystals are not dissociated in ions.
Description : What is the physical state of water at 12° C? (1) Gas (2) Solid (3) Liquid (4) Ionic
Last Answer : (3) Liquid Explanation: Water can occur in thretates solid (ice), liquid gas (vapor). It is liquid at 12 Celsius. This is the form water with which we are most familiar.