(One hour and a half)
_______________________________________Section I is Compulsory and attempt any four questions from Section II.
The intended marks for questions or parts of questions, are given in brackets [ ]
________________________________________
SECTION I (40 Marks)
Compulsory: To be attended by all candidates.
Question 1
a) Answer the following questions relating your answer only to the gases in the list given below:
Ammonia, hydrogen chloride, Sulphur Dioxide, Nitrogen, Oxygen, hydrogen, nitric oxide, methane, ethane.
i) Two gases which react under relevant conditions to give a gas which turns a solution of potassium mercuric or iodide brown.
ii) A gas which is absorb by iron[II] sulphate solution to give a brown addition compound.
iii) Two gases which react to give a reddish brown acidic gas.
iv) Two gases which react in presence of a catalyst at elevated temperatures to give an alcohol.
v) Two gases which react to give a solid which reacts with an alkali to give back one of the reactant gases. [5]
b) The following questions pertain to chemical bonding :
i) Differentiate between the terms -- ' electrovalent bond' and 'covalent bond'.
ii) Draw the electron dot structure and orbit structure to depict the formation of
A) Sodium chloride.
B) Carbon tetrachloride.
[²³₁₁Na, ³⁵₁₇Cl, ¹²₆C] [6]
c) In this question you are required to supply the word/s that will make each sentence into a correct statement which is to be written down in full.
Example: Magnesium nitride reacts with water to liberate ammonia.
Answer: Magnesium nitride reacts with warm water to liberate ammonia.
i) Activity series is a series arranged according to their decreasing reactivity.
ii) Ammonia reacts with lead[II] oxide liberating nitrogen.
iii) Aqua regia contains one part of a night ride nitric acid and three parts of nitric acid and three parts of hydrochloric acid.
iv) Ethyl alcohol is dehydrated by sulphuric acid at elevated temperatures liberating ethene gas.
v) Anions migrate during electrolysis and get discharged. [5]
d) i) Give a reason why pure water is termed as a non-electrolyte while acidified what is an electrolyte.
ii) Name the product formed at the anode during electrolysis of aqueous sodium silver cyanide solution.
iii) State which of the following salt is weak electrolyte--
Silver nitrate, Sodium carbonate, Copper chloride.
iv) State which of the following substance contains both ions and molecules ---
Sodium hydroxide solution, Acetic Acid, molten lead bromide.
v) Write the equation for the reaction which takes place at the anode during electrolysis of acidified water. [5]
e) i) What is the empirical formula of compound having the following percentage composition :
Fe= 73.38% and O= 27.62% [Fe=56, O=16]
ii) Iron pyrites [FeS₂] on roasting in air [oxygen] give iron[III] oxide and Sulphur dioxide. Calculate the weight of iron pyrites which must be roasted to produce 5000 g. of Sulphur dioxide gas. [S= 32].
iii) Combustion of ethane yields carbon dioxide and water vapour. Calculate the volume of carbon dioxide form that STP and the number of moles of oxygen needed for the combustion of 60 g of Ethane. [8]
f) What do you see when:
i) Bromine is passed into a solution of ethyne in an inert solvent.
ii) Ammonia-oxygen mixture is passed over the heated Platinum.
iii) Le[II] oxide is reacted the dilute nitric acid and the residual solution formed is mixed with sodium chloride solution.
iv) Zinc nitrate is heated strongly in air.
v) Hydrogen sulphide gas is bubbled through concentrated sulphuric acid and the gas liberated is then bubbled through iron[III] sulphate solution.
vi) Excess ammonium Hydroxide is added to the solution formed on reaction between lead carbonate and dilute nitric acid is excess. [6]
g) Write balanced equations for each of the following reactions involving an oxide.
i) Lead[IV] oxide and concentrated hydrochloric acid.
ii) Lead [II] oxide(heated) and Ammonia.
iii) Zinc oxide and dilute nitric acid.
iv) Sodium oxide and Sulphur dioxide.
v) Iron [III] oxide and Aluminium. [5]
SECTION II (40 Marks)
Attempt any 4 questions
Question 2
a) Define the following periodic properties.
i) Ionization potential.
ii) Electronegativity. [2]
b) State the following pertaining to the Periodic Table.
i) The period of the Periodic Table which has two elements in its period.
ii) The period to which the element carbon belongs.
iii) The elements in period 2 with the highest and potential.
iv) The noble gas present in period 2 of the Periodic Table. [4]
c) Supply the missing word/s in the blanks below.
Sodium is an___metal belonging to group______of the Periodic Table. It has _____ electron/s in its valence shell and is a strong _____ agent. [4]
Question 3
a) Differentiate between the following terms:. [3]
i) Basicity of acids and acidity of based.
ii) Concentrated acid and strong acid.
iii) Dibasic acid and diacidic base.
b)i) Define a metal and a non-metal on basis of Ionization.
ii) Compare a metal and a non-metal on basis of reaction with dilute acids.
iii) State a characteristic property of 'alkali metals' present in Group I A with a specific reason for the same. [3]
c) i) Name an ore of sulphur used in the Contact Process which on roasting yields sulphur dioxide gas
ii) Name the gas evolved when zinc reacts with the final product of Contact Process. [2]
d) State which chemical property of sulphuric acid is involved in the following conversion:
i) Nitre to aqua fortis.
ii) Hydrogen sulphide to sulphur. [2]
Question 4
a) Give the IUPAC name and common name of the following hydrocarbons--
i) CH₄
ii) C₃H₆ [2]
b) i) Give a reason why the compound in a(i) above is called saturated organic compound.
ii) State the characteristic and typical reactions of the organic compound in a(i) above.
iii) Draw the electronic structure of the organic compound C₂H₂. [3]
c) i) Name the first chlorination product obtained when CH₄ and C₂H₆ react with chlorine respectively.
ii) What is the special feature of C₂H₄ and C₂H₂ which differentiates them from the hydrocarbons in a(i) above.
iii) What type of reactions undergone by the compounds C₂H₄ and C₂H₂.
iv) What is added to ethyl alcohol to obtain ethene in its laboratory preparation. [5]
Question 5
a) What must be added to sodium chloride in the laboratory preparation of Hydrogen chloride gas. [1]
b) Write the equation for the reaction which takes place in (a) above. [1]
c) Starting from hydrochloric acid how would you obtain --
i) Chlorine using lead [IV] oxide.
ii) Chlorine using bleaching powder.
iii) Carbon dioxide using a soluble metallic carbonate.
iv) Hydrogen sulphide using a metallic sulphide. [4]
d) Name the following:
i) A salt formed when hydrogen chloride reacts with heated iron.
ii) The oxidizing agent in Aqua regia.
iii) A metallic chloride insoluble in water and dilute nitric acid but soluble in liquor ammonia solution.
iv) The neutral gas obtained when hydrogen chloride undergoes thermal dissociation. [4]
Question 7
a) Calcium nitrate decomposes on heating to give calcium oxide, nitrogen dioxide and oxygen.
i) Write the balanced equation for the thermal decomposition.
Calculate:
ii) The volume of Nitrogen dioxide obtained at STP.
iii) The weight of the calcium oxide obtained when 4.1 g of calcium nitrate is heated. [Ca= 40, O= 16, N= 14] [4]
b) Ammonia burns in oxygen of the air with a yellowish green flame, forming nitrogen and water as the only products.
i) Write the balanced equation for burning of ammonia in oxygen.
ii) Determine the volume of oxygen used and the volume of Nitrogen obtained when 400cc of ammonia burns in oxygen. [4]
c) Calculate the percentage of oxygen in nitre. (K=39, N= 14, O=16). [2]
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