FIRST YEAR HIGHER SECONDARY MODEL EXAMINATION FEBRUARY
HSE(1)
Part-III CHEMISTRY
Maximum: 60 Scores
Time: 2 Hours
Cool-off time: 15 Minutes
General Instructions to Candidates
 There is a ‘cool off time’ of 15 minutes in addition to the writing time of 2 hours.
 You are not allowed to write your answers nor to discuss anything with others during the
‘cool off time’.
 Use the ‘cool off time’ to get familiar with questions and to plan your answers.
 Read questions carefully before answering.
 All questions are compulsory and only internal choice is allowed.
 When you select a question, all the sub questions must be answered from the same question
itself.
 Calculations, figures and graphs should be in the answer sheet itself.
 Give equations wherever necessary.
1 Methane (CH4) burns in oxygen according to the following equcation
CH4 + 2O2
→ CO2 + 2 H2O
.
If 4g methane burns in 10g oxygen
(a) What is the amount of CO2 formed
(2)
(b) Identify the limitting reagent
(1)
( c) Calculate the amount of reactant which is unreacted
(1)
2 A student wrote the electronic configration of carbon as 1S22S22Px2 for the class test but the teacher
marked it wrong,
(a) Which rule is violated by writing the electonic configration as above . State the rule
(2)
(b) There are 2 electons in the 3d orbital of an element . What is the atomic number of the
element?
3
Consider the following species: N3−, O2−, Na+, Mg2+, Al3+
(1)
(a) What is common in them?
(1)
(b)Arrange them in the increasing order of Ionic radii.
(1)
(c)The Ionization energy of nitrogen is greater than that of oxygen. Justify
(2)
4. Complete the following table
No
Molecule
1
2
3
CH4
H2O
SF6
No.of
l.p e0
……
0
No. of
b.p e………
2
…….
Shape
Tetrahedral
V-shape
…….
Bond
angle
…….
…….
900
(6x1/2 = 3 )
b) Bond order is one half the difference between the number of electrons present in the bonding and
antibonding molecular orbitals.. Calculate the bond order of oxygen molecule and predict its
stability and magnetic property.
(3)
5
After discussing the Daltons law of partial pressures Student A wrote CO2 and O2 as examples of
gaseous mixtures obeying Daltons law while Student B wrote NH3 and HCl as examples.
(a) Who wrote the correct answer?
(1)
(b) State Dalton’s law of partial pressures
(2)
(c) Give the Vander Waal’s equation and explain each term in it.
(2)
6 A sample of river water does not give lather with soap easily when it is cold. But on heating it gives ready
Leather
(a) Account for this and write the chemical equations involved
( 2+2= 4 )
7 A student while doing experiment in the lab , a piece of metallic sodium happened to fall into liquid
ammonia kept in a beaker.
(a) What change will the student obsrve in the beaker
(b) Give reason for this change
(1)
(2)
8 At atmospheric pressure ice melts only if the temperature rises above 00C
(a)Give the signs of ΔH and ΔS during melting.
(1)
(b) Write Gibb’s – Helmholtz equation and explain the terms.
(2)
( c) . Enthalpy of formation of CO(g) , CO2(g) , N2O(g) and N2O4(g) are -110 , -393 , 81 and 9.7 KJmol-1
respetively . Find the value of ΔHr from the reaction.
9 Diamond and Graphite contains carbon but properties are different . Explain that properties with its
reason
10. For the equilibrium, 2NOCl (g)
→
(2)
(3)
2NO (g) + Cl2 (g), the value of the equilibrium constant, Kc is
3.75 X 10-6 at 1069K. Calculate Kp for the reaction.
(3)
11 Oxidation number increases during oxidation and it decreases during reduction
(a) Calculate the oxidation number of Sulphur in H 2S and SO2
(b) Mg and O2 react to give MgO according to the equcation 2Mg +O 2
(2)
→ 2MgO
Idenify oxidising agent and reducing agent
(1)
12 The two isomers of C5H12 are
(i) CH3- CH2- CH2- CH2- CH3
(ii)
CH3- CH- CH2- CH3
CH3
(a) Give the IUPAC names of the above isomers
(2)
(b) Explain metamerism with suitable example
(2)
13. Draw the structure of
(a) Pent- 4-en-2-ol
(b) 6- hydroxy heptanal
( c) 3 -Chlorohexane
14 ( a) Draw Sawhorse and Newmann’s Projections of the different conformers of ethane.
(b) During electrophilic substitution reactions Phenol is ortho para directing. Justify
(3)
(3 )
(3)
15 CO and CO2 are gases which causes air polution
(a). CO gas is more dangerous than CO2 gases. Explain ?
(2)
(b).The Coppen Hagen summit on global warming 2009 was a failure. Suggest some measures to overcome
global warming.
Prepared by FIROZ. K.K AND ZEENATH. U
P.P.M.H.S.S KOTTUKKARA ,
(2)
(HSST Chemistry)
(11057), KONDOTTY, MALAPPURAM.