1015813049 Chem

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Guess Paper 2011

Class XSubject Chemistry

Section 1

Q1

a)Name the gas produced:

i) Iron pyrites are roasted. SO2

ii) Magnesium reacts with very very dil. Nitric acid. H2iii) Hydrochloric acid reacts with Manganese dioxide. Cl2

iv) Nitric acid Decomposes. No2,O2

v) Zn reacts with conc.sulphuric acid.H2 [5]

b)Fill in the blanks

i) __H2SO4_______ is the king of chemicals.

ii) __Bauxite________ is the chief ore of Al.iii) __Ethene_______ is the first compound of alkenes.

iv) __H2CO3________ is a mineral acid having carbon in it.

v) _Efflorescence_______ is the proprety of losing water of crystallization.[5]

c)

Write balanced equationi)Sodium thiosulphate is warmed with HCl.

ii)Water is added to oleum.iii) Ethyne is produced from dibromoethane.

iv)Cu reacts withdil nitric acid.v)Al is added to NaOH. [5]

d)How would you distinguish

i)HCl & HNO3. Adding AgNO3

ii)PbSO4 & MgSO4. Adding NaOH in excessiii)Ca(OH)2 &CuSO4. Adding NH4OH

iv)ZnCl2 &PbCl2. Adding NH4OH in excess.

v)ethyne & ethane. Adding Alkaline KMnO4 [5]

e)Matching

i)Polymerisation 1)Ethane to CO2 & H2O

ii)Extraction of Al 2)Brown rings test

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iii)Combustion 3)ethene to polyethene

iv) Test for nitrates 4)Baeyers process

v)H2SO4 5)Contact Process [5]

i-3 ii-4 iii-1 iv-2 v-5

f)

Na,P,H2SO4,Coke(carbon),NO2

i)A reddish brown gas NO2

ii)A metal stored in kerosene Na

iii)A reducing agent Coke

iv)A non-metal used in alloys P

v)Least volatile acid H2SO4 [5]

g)

Calculate

i)no of molecules in 40g of He. 6.022 x 10(Avogardo,s no).

ii)no of gram-atoms in 1kg of CaCO3. 10

iii)percent of nitrogen in urea.[NH2CONH2] 46.66% [5]

h)

Elements A & B react with Cl and O to form ACl and BO.

i)Identify the family of A. Alkaline metals.

ii)Identify the family of B. alkaline earth metals

iii)Which is more metallic A or B?A

iv)Arrange A,B,Cl,O in increasing order of atomic size.(A and B,Cl are in same

period)

Cl

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v)Arrange A,B,Cl,O in increasing order of electronegativity. [5]

A

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Galvanisation is the process of coating of an iron layer with zic layer to prevent rusting.[1]

iv)Which metal is used in (iii) and write the reaction.. [2]

Zn+H2OZnO + H2

b)

Distinguish

i) Efflorescence and Deliquescence.(Loss of H2O and absorption of H2O)

ii) Ionisation energy and Electron affinity(Energy to remove e- & energy to add e-)

iii) Roasting and calcinations.(Prescence of O2 & Absence of O2)

iv) Ionisation and dissociation.(Polar covalent compounds & Ionic compounds) [4]

Q4)

a) Give reasons:

i) The blue colour of CuSO4 fades on electrolysis using Platinum electrodes.Cu ions

migrate to cathode.

ii) Acetic acid is known as glacial acetic acid. At 290K it freezes to form crystals

ressembling ice.

iii)Charring is observed when conc H2SO4 is poured on wood.H2SO4 showsdehydration property.

iv)A yellow solution is found when nitric acid is left in a tube.Dissolution of NO2.

v) Atomic size decreases on moving right in a period.Nuclear charge increases

vi) Covalent compounds have low melting and boiling points.Weak forces ofattraction. [6]

b)

i)The most electropositive element is __Cs_______.

ii)The biggest element.is __Cs_____.-------------------------------------------------------------------------------------------------------

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iii)The halogen with highest electron affinity is ___Cl____.

iv)The first alkyne is _Ethyne__.[4]

Q5)

a) Explain Habers process. N2+3H2(Fe/Mo)(200-900atm)(450-500oC)>2NH3

[4].

b) i) Calculate the % loss of mass of aqueous (CuSO4),when it is completely

dehydrated by conc H2SO4.36.07%

ii) An organic gas has the following % composition:C=82.76%,H=17.24%.

Its vapour density is 29.Find its empirical formulae.[C=12,H=1 ].

C2H5 [6]

Q6)

a) Define:

i)Gangue.-Earthly impurities like silica present in the ore is known as Gangue.

ii)Periodicity- The phenomenon of the repetition of properties at regular intervals isknown as Periodicity.

iii)Dative bond.-The bond formed when an atom completely donates a lone pair of

electrons to an ion.

v)Molar Volume.-The volume occupied by 1 mole of a gas at S.T.P conditions.

vi)Electrolysis.-The dissociation of an ionic compound brought about by passing

electric current is known as Electrolysis. [6]

b)

Acetic acid can be prepared by (i) oxidation of acetaldehyde,(ii)Hydrolysis of ethyl

acetate. Write equations for these preparations. [4].

CH3CHO +[O] ==(Alkaline KMnO4)=>CH3COOH

CH3COOC2H5 + H2OCH3COOH +C2H5OH

Q7)



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a)Write equations for action of heat on:

(i) Ammonium chloride-NH4ClNH3+HCl

(ii) Ammonium nitrate. NH4NO3N2O+H2O

(iii) Ammonium nitrite. NH4NO2N2+H2O

b)

What happens when

i)conc HNO3 is added to Cu |Cu+4HNO3Cu(NO3)2+2H2O+2NO2

ii)H2SO4 is added to oxalic acid.CO &CO2 are formed. [2]

c)i) Name two explosives from HNO3.

ii)Two Hydra-acids. HCl & HF [2].

Paper Submitted By:

Name Mr. G.Hemanth

Email Id [email protected]



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1015813049 Chem