Tag: neco chemistry expo 2020

NECO CHEMISTRY ANSWERS 2020 Here is the chemistry answers UPDATED, all you have to do is refresh this page, and make sure you share it, just tap on the social media icon at the end of this post to share. NECO THEORY CHEMISTRY ANSWERS (1ai) (i)graphite (ii)diamond (1aii) (i)animal charcoal (ii)carbon black (1aiii) (i)The property of elements are a periodic function of their atomic number (ii)Elements are arranged in the periodic table according to the order of increasing in their atomic weight. (1bi) Periodicity can be defined as the trend or recurring variation in element properties with increasing atomic number. (1bii) using; mole no; of atoms/avogadro's constant 0.5no; of atoms/6.023*10²³ no; of atoms 0.5*6.02*10²³3.012*10²³atom 1ci) Faraday's first law of electrolysis state that the chemical deposition due to the flow of current through an electrolyte is directly proportional to the quantity of electricity (coulombs) passed through it. (1cii) 2O²^- + 9^e --->2O² no; of electron 4 Q20300C G.M.V 22.4dm³. F96500C MoleQ/n,f Mole20300/4*96500 Mole20300/386000 Mole0.05mol Recall; vol/G.M.V 0.05vol/22.4 vol0.05*22.4 vol1.12dm³ (1di) Using H²SO⁴ H+ SO⁴^-¹ H+ OH^- A+ Anode OH ----> OH + e^- 2OH+(aq)+2OH(aq)---->2H²O(s)+O²(aq) (1dii) Tabulate -Electrolyte- (I)teraoxosulphate(iv)acid (II)Ester -non electrolyte- (III)phenol (1ei) (i)mercury (1eii) (I)no; of electron in Y 16 (II)no; of mass number 16+1834 (III)sulphur (2ai) basicity can be defined as the number of replaceable hydrogen ion in an acid (2aii) (I) ---> 3 (II) ---> 1 (III) ---> 2 (2bi) (i)Concentration (ii)Temperature (iii)Pressure (2bii) (i)Light (ii)Temperature (iii)Nature of reactant (2ci) Tabulate S/N; (I), (II) Indicator; methyl orange, phenolphthalein Colour in acid; red, colourless Colour at end point; orange colourless Colour in base; yellow, pink Suitable for; strong acid and weak base, weak acid and strong base (2cii) (i)Nitrogen ---> 1s²,2s²,2p³ (ii)Fluorine ---> 1s²,2s²,2p⁵ (iii)Aluminum ---> 1s¹,2s²,2p⁶,3s²,3p¹ (2di) (I)Hydrogen gas is liberated (II)The purple colour turns colourless (III)It leads to the deposit of black residue of carbon (2dii) (i)It serve as immediate source of energy (ii)it is used in the manufacture of sweets. (4ai) (I)Burning requires heating while corrosion does not (II)Boiling occurs at a certain temperature while evaporation occurs at all temperature (4b) A concentration solution can be defined as a solution formed when a large quantity of a substance dissolves in a little volume of water (4bii) (i)position of ion in electrochemical series (ii)concentration ion (iii)nature of electrodes (4ci) Al²(SO⁴)³(27*2)+(32*3)+(16*12) 54+96+192342glmol (4cii) Aluminum teraoxosulphate (iv) (4ciii) (i)Propane - 1,2,3,- triol (ii)Potassium salt (4di) Tabulate. -Soaples detergent- (i)it does not form scum in hard water (ii)they are non-biodegradale -Soapy detergent- (i)It firm scum in hard water (ii)They are biodegradable (4dii) (i)RCOOH (ii)ROH (4diii) V1300cm³. P1760mmHg P2800mmHg, V2? Using; V1*P1 V2*P2 300*700V2*300 V2300*760/800 V2228000/800 V2285cm³ (4div) Its change is +3 (4dv) Al³^+ (Aluminum ion) (5ai) Coal and coke (5aii) (I)acidic --- NO² nitrogen (iv) oxide (II)neutral --- NO nitrogen (ii) oxide (5aiii) HCOOH. H²SO⁴/H²O CO(g) 46g of HCOOH 22.4dm³ of CO 600g of HCOOH X X 600*22.4/462.92dm³ of CO(s) is produced. (5bi) (i)To standardize a solution of an acid or base (ii)To determine the percentage purity and impurity of an acid of a base (5bii) (I)density (II)solubility (5ci) FeCl²(s) + 2NaOH(aq) ----> 2NaCl²(aq) + Fe(OH)²(s) The main product is sodium chloride and iron (II) hydroxide (5cii) (I)FeCl² (II)iron (ii) chloride (5di) (I)it is slightly denser than air (II)it is slightly soluble in water (5dii) Because on exposure to air of rust due to the formation of hydrated iron (iii) oxide. In other words rusting it changes to reddish brown f BMS, laky powder is formed with new properties and irrversable permanent change. Fe(s) + 3O³(g)+ XH²O(s) ---> 2Fe²O³ XH²O(s) (5diii) Mas of dry hydrogen 35g Mass of dry hydrogen + oxygen vapour of a compound 440g Mass of organic vapour of the compound 440g-35g405g V.D of the vapour mass of vapour/mass of equal volume of H² 405/35 11.51 ≅ 11.6 V.D 11.6 R.m.m of the vapour V.D *2 11.6*223.2 (6ai) (I)Efflorescence (II)Isotope (III)Isomerism (6aii) Kipps apparatus (6aiii) (i)Temperature (ii)Enthalpy change value (6bi) Polymerisation can be defined as the arrangement of smaller nuclei to form a large nuclei (6bii) (i)Addition polymerisation (ii)Condensation Polymerisation (6biii) OH^- 4.583r10^⁵ Since 10^-¹⁴ 10^-¹⁴ 1*10^-¹⁴/4.583*10^-⁵ 0.22*10^-⁹ 2.2*10^-¹⁰moldm³ Since; PH - logH^+ PH - log¹⁰ 2.2*10^-¹⁰ PH0.34+10 PH10.34 (6ci) (I) ----> carbohydrate (II) ----> R-OH and R-CHO (6cii) (I)Brass composition; copper and zinc -uses of brass- (i)it is use in making hammers (ii)it is used in application where low corrosion resistance is required. (II)steel composition; iron and carbon -Uses of steel- (i)it is used on roofs (ii)it is used as cladding for exterior walls (6ciii) (i)Fermentation (ii)Preparation from ethene (6iv) This is because there are on molecules in that can accept protons Please use the share buttons below to share, no forget me o, come whatsapp come show me love...good luck