JEE Main Previous Year Papers Questions With Solutions Chemistry States of Matter: Gases,Liquids and Solids
Ans. (3) PV = nRT
Number of moles per litre = n /V Therefore, n / V = P / RT.
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3. Kinetic theory of gases proves (2002)
(1)only Boyle’s law
(2)only Charles’ law
(3)only Avogadro’s law
( 4) all of these
Ans.(4)Postulates of kinetic theory explains all gas laws.
4. The heat required to raise the temperature of body by 1 K is called (2002)
1) specific heat 2) thermal capacity
3) water equivalent 4) none of these
Ans.(2)The heat required to raise the temperature of body by IK is called thermal capacity or heat capacity.
5.Na and Mg crystallize in BCC and FCC type crystals respectively. Then the number of atoms of Na and Mg present in the unit cell of their respective crystal is (2002)
1)4 and 2 2) 9 and 14
3) 14 and 9 4) 2 and 4
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6.How many unit cells are present in a cubeshaped ideal crystal of NaCl of mass 1.00 g ? [Atomic masses : Na = 23, Cl = 35.5] (2003)
1) 5.14 x 1021 unit cell 2) 1.28 x 1021 unit cell
3) 1.71 x 1021 unit cell 4) 2.57 x 1021 unit cell
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7. According to the kinetic theory of gases, in an ideal gas, between two successive collisions a gas molecule travels (2003) l
(1) in a wavy path
(2)in a straight line path
(3)with an accelerated velocity
(4)in a circular path
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8. As the temperature is raised from 20°C to 40°C, the average kinetic energy of neon atoms changes by a factor of which of the following? (2004)
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9.In Van der Waals equation of state of the gas law, the constant ‘b’ is a measure of (2004)(1)intermolecular repulsions
(2)intermolecular collisions per unit volume
(3)Volume occupied by the molecules
(4)intermolecular attraction
Ans.(3) In van der Waals equation, ‘b’ is the excluded yolume. Exculded volume is the volume occupied by the molecules of gas
Ans.(4) Few ion pairs are missing from the given lattice points.
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12.An ionic compound has a unit cell consisting of A ions at the corners of a cube and B ions on the centres of the faces of the cube. The empirical formula for this compound would be (2005)
1) AB 2)A2B 3) AB3 4)A3B
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13. Which one of the following statements is NOT true about the effect of an increase in temperature on the distribution of molecular speeds in a gas ? (2005)
(1)The most probable speed increases
(2)The fraction of the molecules with the most probable speed increases
(3)The distribution becomes broader
(4)The area under the distribution curve remains the same as under the lower temperature
Ans.(2) Most probable velocity increase and fraction of molecule possessing most probable velocity decreases.
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15.An ideal gas is allowed to expand both reversibly and irreversibly in an isolated system. If T. is the initial temperature and Tf is the final temperature, which of the following statements is correct ? (2006)
(1)(Tf)irrevXTf)rev
(2)Tf > Tj for reversible process but Tf = T} for irreversible process
(3)(Tf)rev = (Tf)irrev
(4)Tf = Tj for both reversible and irreversible processes
Ans.(2) Concept of workdone
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18.Copper crystallizes in fee with a unit cell length of 361 pm. What is the radius of copper atom?
1) 108pm 2) 127pm (2009)
3) 157pm 4) 181pm
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21.Percentage of free space in cubic close packed structure and in body centered packed structure are respectively (2010)
1)30% and 26% 2) 26% and 32%
3) 32% and 48% 4) 48% and 26%
Ans.(2) packing fraction of cubic close packing and body centered packing are 0.74 and 0.68 respectively.
22.’a’ and ‘b’ are van der Waal’s constants for gases. Chlorine is more easily liquefied than ethane because (2011)
(1)a for C/2 < a for C2H6 but b for Cl2 > b forc2h6
(2)a for C/2 > a for C2H6 but b for C/2 < b forc2h6
(3)a and b for Cl2 > a and b for C2Hg
(4)a and b for C/2 < a and b for C2H6
Ans.(2) Inter molecular forces and molecular weight is more for CZ2 hence Cl2 has high boiling point than C2H6. But the size of molecule C2H6 is greater than C/2 hence for C2H6 b is greater than C/2.
23.In a face centred cubic lattice, atom A occupies the corner positions and atoms B occupies the face centre positions. If one atom of B is missing from one of the face centred points, the formula of the compound is (2011)
1)A2B3 2)A2B5 3)A2B 4)AB2
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24.Lithium forms body centred cubic streture. The length of the side of its unit cell is 351 pm. Atomic radius of the lithium will be (2012)
1) 75 pm 2) 300 pm 3) 240 pm 4) 152 pm
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25.The compressibility factor for a real gas at high pressure is (2012)
1) 1+RT/Pb 2) 1
3) 1+Pb/RT 4) 1-Pb/RT
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26.For gaseous state, if most probable speed is ‘ denoted by C*, average speed by c and mean square speed by C, then for a large number of molecules the ratios of these speeds are
(1)C* : C : C = 225 : 1.128 : 1 (2013)
(2)C* : C : C = 1.128 : 1.225 : 1
(3)C* : C : C = 1: 1.128 : 1.225
(4)C* : C : C = 1 : 1.225 : 1.128
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27.Which of the following exists as covalent crystals in the solid state? (2013)
1) Iodine 2) Silicon
3) Sulphur 4) Phosphorus
Ans.(2) I2, P4, Sg are molecular crystals Silicon is covert crystal
28.Experimentally it was found that a metal oxide has formula M09g Metal M, is present as M2+ and M3+ in its oxide. Fraction of the metal which exists as M3+ would be (2013)
1) 7.01% 2) 4.08% 3) 6.05% 4) 5.08%
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