Answers to This Paper Must Be Written on the Paper Provided Separately

Guess Paper – 2013

Class – X

Subject–CHEMISTRY

Answers to this paper must be written on the paper provided separately.

You will not be allowed to write during the first 15 minutes.
This time is to be spent in reading the Question Paper.
The time given at the head of this paper allowed for writing the answers

Section I is compulsory.

Attempt any four questions from section II. The intended marks for questions or parts of questions are given in brackets [ ].

SCIENCE Paper-2

(One hour and half)

SECTION I (40 Marks)

Attempt all questions from this Section

Question 1

(a) Give the products formed in each of the following:
(i) The gas formed when sodium ethanoate is heated with sodalime.
(ii) Calcium carbide undergoes hydrolysis.
(iii) Zinc reacts with concentrated sulphuric acid.
(iv) Iron reacts with hot dilute nitric acid.
(v) Iron reacts with cold dilute nitric acid.[5]

(b) How can the following pairs of molecules be distinguished using suitable chemical tests?

(i) Ethane and Ethene.
(ii) Ethene and Ethyne.
(iii) Ethanol and Ethanoic acid
(iv) Dilute Suphuric acid and Dilute Hydrochloric acid
(v) Dilute Nitric acid and dilute Acetic acid.[5]

(c) State reason for the following facts in not more than one sentence.
(i) Bridge elements show similarities in properties diagonally with the period of the next group.
(ii)Acidic character of hydroxides (or oxoacids) and hydrides increase from left to right in a period.
(iii) Reducing nature of group 1 element increases from top to bottom in a group.
(iv) Oxidizing nature of elements increases from left to right in a period.
(v) Although fluorine is most electronegative element, electron affinity of fluorine is lesser than chlorine.[5]

(d) Choose the correct answer from the options given below :

(i) The formula of Phosphate of an element whose atomic number is 20

(A) Mg3(PO4)2

(B) Sr3(PO4)2

(D Ba3(PO4)2

(ii)Which of the following is not a polar covalent compound?
(A) H2O

(B) CO2

(D) 0.1

(iv)Which of the following compound can’t form coordinate bond with NH3 ?

(A) BCl3

(B) AlCl3
(C) CuSO4 (aq)
(D) CaSO4 (aq)

(v) Dilute nitric acid produces hydrogen gas with which of the following element?
(A) Mn

(B) Fe

(D) All of the above.[5]

(e)Draw the branched structural formula of the organic compounds whose IUPAC names are given below.

(i) 2-Bromo-4-chloropentane

(ii) 2, 2-Deimethylpropane

(iii) 2-Methylbutan-2-ol

(iv) 1, 1, 2, 2-Tetrabromoethane

(v) 2-Methyl-prop-1-ene[5]

(f) Answer the following questions related to extraction of Aluminium from Bauxite.
(i) Give the reaction involved in the Baeyer’s Process.

(ii) What is seeding ?

(iii) Why is cryolite mixed with alumina during Hall Heroult’s process?
(iv) Give the reaction at cathode in Hall Heroult’s process of reduction of Alumina.
(v) How is Hoope’s process entirely different from Hall Heroul’s process?[5]

(g) (i)Give the balance chemical equation for complete combustion of Octane.

(ii) How many moles of carbon dioxide are produced when one mole of octane burns?

(iii) What volume at STP is occupied by the number of moles determined in (ii) i.e CO2?

(iv) What is the mass of CO2 produced when 2-moles of octane is burnt?

(v) What is the empirical formula of octane?[5]

(h) Name the following:

(i) The process used for concentration of specially sulphide ores:

(ii) The process used for converting sulphide ore to oxide ore by heating in presence of air.

(iii) The process used for converting carbonates to oxide ore by heating in absence of air.

(iv) The substance which combines with the gangue to form separable slag from Iron ore

(v) The process in which Al and Fe2O3 is made to undergo exothermic displacement reaction. [5]

SECTION – II (40-Marks)

Attempt any four question from this section

Question 2

(a) Given below is a flow chart for the preparation of nitric acid on a large scale.

(i) Write the reaction that takes place in the catalyst chamber , oxidation chamber and Absorption chamber.

(ii) What is the name of the process shown the above flow chart.

(iii) Name the catalyst used in the catalyst chamber.[3+1+1]

(b) Give the balanced chemical equation for the following reaction.

(i) HNO3 + 3HCl  ______+ ______+ [ ]

(ii) P + conc. HNO3  ______+ ______+ _____ (g)

(iii) Cu + conc. HNO3  _____ + _____+ _____(g)

(iv) (NH4)2CO3 + conc. NaOH  ____ + ______+ ______(g)

(v) NH4OH + K2[HgI4]  ______+ ______[5]

Question 3

(a)Give the observation for each of the following case:

(i) Nitrogen dioxide gas is passed through KI solution.

(ii) Hydrogen sulphide gas is passed through acidified potassium permanganate solution.

(iii)Sulphur dioxide gas is passed through acidified potassium dichromate solution.

(iv) Oxygen gas is passed through alkaline pyragallol solution.

(v) water is added to anhydrous cobalt chloride.[5]

(b) (i) Give the percentage composition of Brass, Bronze and German Silver.
(ii) Give any one use each of Solder and Duralumin. [3+1+1]

Question 4.

(a) Copy and fill the blanks in the tabular format to show what happens when the given cations are treated with

Few drops of NaOH solution, Excess of NaOH solution, few drops of NH4OH solution and Excess of NH4OH.

Serial No. / Cations in the salt solutions / Observation Parameters / When few drops of
NaOH solution
Is added / When excess of NaOH solution is added / When few drops of NH4OH solution is added / When excess of NH4OH solution is added
(i) / Ca++ / Mol. Formula
Colour/ppt./soln.
(ii) / Zn++ / Mol. Formula
Colour/ppt./soln.
(iii) / Fe++ / Mol. Formula
Colour/ppt./soln.
(iv) / Cu++ / Mol. Formula
Colour/ppt./soln.

[4]

(b) A solution has P has pH =13 ; solution Q has pH=6 and solution R has pH=2.

(i) Which solution can make ammonia to be liberated from ammonium sulphate?

(ii) Which solution is a strong acid?

(iii) Which solution contains solute molecules as well as ions?[3]

(i) Methane.

(ii) Ammonium ion.

(iii) Ozone.[3]

Question 5.

(a) Carbon was made to react with hot, conc. Sulphuric acid.

(i) Write the balanced chemical reaction for the reaction indicated above.[2]

(ii)Calculate the mass of Carbon oxidized by 49g of sulphuric acid.[2]

(iii) Calculate the volume of gases measured at STP evolved at the same time.[2]

(b) The following question refers to the scheme given below. Write one chemical equation in each case for a reaction which could bring about each of the changes A,B,C and B

[4]

Question 6

(a) A compound has the following % composition: C=40%, H=6.7%, O=53.3%, the vapor density of the compound is 30, determine its Empirical formula and molecular formula. [3+1]

(b) The above compound is found to show pH=3 and produces CO2 gas with NaHCO3, Give the structural formula, IUPAC name and common name of the molecule. [3]

(i) Methyl Orange
(ii) Blue litmus

(iii) Alkaline Phenolphthalein[3]

Question 7

The following questions are based on preparation of Hydrogen chloride gas in the laboratory.
(a)(i) Why NH4Cl can’t be used in place of NaCl to prepare HCl gas.
(ii) Why conc. H2SO4 is preferred as a drying agent for preparation of HCl gas.
(iii) Why conc. Nitric acid can’t be used to react with NaCl to form HCl gas.
(iv) Why HCl gas can’t be collected by downward displacement of water.[4]

(b) What happens when : (i) HCl gas is passed through dil. AgNO3 solution

(ii) Glass rod moistened with NH4OH solution is brought near HCl gas.

(iii) Moist blue litmus paper is brought near dry HCl gas.[3]

(c) (i)Give the solubility ratio of HCl(g) in water.
(ii) Why there is a tendency of back suction of water during dissolution of HCl gas in water?

(iii) How does special funnel arrangement prevent back suction of water?[3]