JEE Main Chemistry

Following are model questions for JEE Main Chemistry examination. These are called as ‘More than one correct answer questions’. You can practice these questions to secure good marks in the IIT JEE Main exam (New Pattern) to be conducted by Joint Admission Board of IITs. Answers are available at the end of the questions.

1. If temperature of a gas is raised, which of the following would be true?
A) Fraction of the molecules possessing most probable velocity will increase
B) Fraction of the molecules possessing most probable velocity will decrease
C) Fraction possessing very low velocity will decrease
D) Fraction possessing very high velocity will increase

2. Correct statements are
A) molar volume of every gas at STP is 22.4L
B) Under critical states compressibility factor is 1
C) All gases will have equal value of average KE at a given temperature.
D) at absolute zero, KE = 3/2 R.

3. From Maxwell Boltzmann distribution curve, the conclusions are
A) there is only a small number of molecules with very low velocities or very high velocities
B) largest number of molecules have a velocity corresponding to the maximum of the curve, which is most probable velocity
C) most probable velocity decreases on increasing temperature
D) distribution of the molecules in the given velocity range decreases on increasing temperature.

4. The molecules that will have dipole moment are
A) 2, 2-dimeethylpropane B) cis-3-hexene
C) 2, 2, 3, 3-tetramethylbutane D) trans-2-pentene

5. Which of the following statements is/ are incorrect regarding two organic compounds A and B which are stereoisomers?
A) They must be enantiomers B) They must be geometrical isomers
C) They can be diastereomers D) They can be meso compounds

6. Which are not isomers?
A) Methanol and methoxy methane
B) Ethyl alcohol and diethyl either
C) Acetone and acetaldehyde
D) Propionic acid and methyl acetate

7. About mesotartaric acid which of the following statements is/ are not correct?
A) It is optically inactive because it contains 2 asymmetric C atoms in its molecule
B) It can be separated into two optically active isomers
C) It cannot be separated into two optically active isomers
D) It is optically inactive due to external compensation

8. Which of the following statements is/ are true about the quantum numbers n, l , m and s?
A) l gives an idea of the shape of the orbital
B) m gives the information of the energy of electron in a given orbital
C) n gives the idea of the size of the orbital
D) s gives the direction of spin of electron in an orbital

9. Which of the following is correct under the same conditions of pressure and temperature?
A) Hydrogen diffuses 4 times faster than oxygen
B) Hydrogen diffuses 2.83 times faster than methane
C) Helium escapes at a rate 2 times as fast as methane does
D) Helium escapes at a rate 4 times as much as sluphur dioxide

10. Select incorrect statements
A) Molar volume of every gas at STP is 22.4L
B) Under critical states compressibility factor is 1
C) All gases will have equal value of average KE at given temperature.
D) At absolute zero, KE is 3/2 R.

KEY: 1) BCD 2) AC 3) ABD 4)BD 5)AB 6)ABC 7) ABD 8) ACD 9) ABCD 10) BD.

Here are some model questions from Physical Chemistry useful for JEE Main / Advanced examinations to be conducted from the academic year 2013-14. Answers also given at the end of the questions.

1. Assertion (A) : Cupric copper is paramagnetic
Reason (R) : Charge of one mole of cupric is two Faradays
1) Both A and R are true, R properly explains A
2) Both A and R are true, R does not explain A
3) A is true, but R is false
4) A is false, but R is true

2. In one of the Bohr’s hydrogen orbit electron revolving with a wavelength of 10A0. The kinetic energy of the electron is
1) 13.6 eV 2) 10.2 eV 3) 3.4 eV 4) 1.5 eV

3. In order to fill all the electrons of chromium (Z=24), number of orbitals required per atom is
1) 12 2) 13 3) 15 4) 24

4. Bond length of HCl is 1.275A° and experimental dipolemoment is 1.03D. The percentage ionic character of HCl is approximately
1) 16.8 2) 50.2 3) 66.7 4) 92.4

5. Aluminium fluoride is more ionic than aluminium chloride. This is because
1) Al is trivalent 2) Al3+ has high polarisation ability
3) F– is small in size 4) Cl – is less polarised

6. The ratio of pure and hybrid orbitals used for bonding in ethylene molecule
1) 1 : 1 2) 1 : 3 3) 3 : 1 4) 3 : 2

7. Ionic, covalent, dative and hydrogen bonds are all present in
1) ammonium chloride 2) epsom salt
3) potassium ferricyanide 4) sodium cyanide

8. Mayer’s relation Cp – Cv = R, can be applied for noble gases. Then the molar heat capacities at constant pressure and at constant volume are respectively
1) 1.5 R and 2.5 R 2) 2.5 R and 3.5 R
3) 3.5 R and 4.5 R 4) 4.5 R and 5.5 R

9. Under similar condition, the liquid that has highest vapour pressure among the following is
1) Diethyl ether 2) Ethanol
3) Acetic acid 4) Water

10. Packing density in the case of metal with face centered cubic structure is
1) 73% 2) 68% 3) 52% 4) 43%

11. 17 grams of hydrogen peroxide is present in 560ml of aqueous solution. This solution is called
1) 10 volumes 2) 17 volumes 3) 20 volumes 4) 34 volumes

12. Molecular weight of a bivalent metal chloride is 136.4. Then equivalent weight of the metal is
1) 26.2 2) 32.7 3) 52.4 4) 65.4

13. 100ml of pure phosphine is decomposed to produce phosphorous solid and hydrogen. Under similar conditions of measurement, the volume
1) increases by 50ml 2) decreases by 50ml
3) increases by 150ml 4) decreases by 150ml

14. The mass of natural water that has one mole of deuterium oxide (called heavy water) is
1) 1.2 kg 2) 12 kg 3) 120 kg 4)1200 kg

15. Weight percentage of chlorine in an alkali metal chloride is 48%. The atomic weight of the metal is likely
1) 56 2) 39 3)19 4)7

16. Regarding oxidation numbers, which of the following is false
1) Oxidation number of metal in metal carbonyl is zero
2) Oxidation number of oxygen in a super oxide is fractional
3) Fluorine exhibits –1 oxidation state
4) The sum of oxidation number of all atoms in an ion is equal to charge of ion

KEY: 1) 2 2) 4 3) 3 4) 1 5) 3 6) 1 7) 2 8) 3 9) 1 10) 1 11) 1 12) 2 13) 1 14) 3 15) 2 16) 1 .