Important formulae from Physical Chemistry for JEE, WBJEE and UPSEE

Chemistry is a very important subject for any engineering entrance examination i.e., JEE Main, JEE Advanced, UPSEE, WBJEE, VITEEE, SRMJEEE etc. The number of questions asked from Chemistry subject in JEE Main and JEE Advanced are 30 and 36 (18 in each paper) respectively. While in UPSEE and WBJEE, the number of questions asked is 50 and 40 respectively.

We can broadly divide the Chemistry into three parts i.e.,

1. Physical Chemistry

2. Organic Chemistry

3. Inorganic Chemistry

About 35% of the total number of questions asked in any engineering entrance exam is from Physical Chemistry. Therefore, Physical Chemistry is a very important part of Chemistry subject.

JEE Main 2018: Application Form, Dates, Syllabus, Papers and Mock test

In this article, we are going to provide you some formulae of Physical Chemistry which are very important from the point of view of the examination.

1. Basic Concepts of Chemistry:

Students can find some questions based on the above formulae given below:

Question:

Solution:

Question:

Solution:

2. Structure of Atom:

Students can find some questions based on the above formulae given below:

Question:

The wavelength of second Balmer line in Hydrogen spectrum is 600 nm. The wavelength for its third line in Lyman series is

(A) 800 nm

(B) 600 nm

(C) 400 nm

(D) 120 nm

Solution:

Question:

Solution:

3. States of Matter:

Students can find some questions based on the above formulae given below:

Question:

At a certain temperature, the value of the slope of the plot of osmotic pressure (∏) against concentration (C in mol L–1) of a certain polymer solution is 291R. The temperature at which osmotic pressure is measured is (R is gas constant)

(A) 271°C

(B) 18°C

(C) 564 K

(D) 18 K

Solution:

We have,

Question:

A certain container holds 3.87 g neon at STP. What mass of neon will it hold at 100°C and 10 atm?

(A) 28.2 g

(B) 32.4 g

(C) 24.5 g

(D) 18.6 g

Solution:

4. Thermodynamics:

Students can find some questions based on the above formulae given below:

Question:

For the reaction X₂Y₄(I) → 2 XY₂(g) at 300 K the values of ΔU and ΔS are 2 kCal and 20 Cal K¹ respectively. The value of ΔG for the reaction is

(A) – 3400 Cal

(B) 3400 Cal

(C) – 2800 Cal

(D) 2000 Cal

Solution:

We have the reaction,

X₂Y₄(I) → 2 XY₂(g)

5. Equilibrium:      

Students can find some questions based on the above formulae given below:

Question:

Solution:

Question:

In which of the following mixed aqueous solutions pH = pKa at equilibrium?

(1) 100 ml of 0.1M CH3COOH + 100 ml of 0.1M CH3COONa

(2) 100 ml of 0.1M CH3COOH + 50 ml of 0.1M NaOH

(3) 100 ml of 0.1M CH3COOH + 100 ml of 0.1M NaOH

(4) 100 ml of 0.1M CH3COOH + 100 ml of 0.1M NH3

(A) (1) is correct

(B) (2) is correct

(C) (3) is correct

(D) Both (1) and (2) are correct

Solution:

Hence, (1) is correct.

Hence, (2) is correct.

6. Solutions:

Students can find some questions based on the above formulae given below:

Question:

Lowering of vapour pressure is highest for

(a) 0.1 M BaCl₂

(b) 0.1 M glucose

(c) 0.1 M MgSO₄

(d) urea

Solution:

Lowering of vapour pressure is directly proportional to the Van't Hoff factor (i).

For BaCl₂,i = 3 (maximum)

Thus, BaCl₂ has highest value relative lowering of vapour pressure.

Hence, the correct option is (a).

Question:

Solution:

7. Electrochemistry:

Students can find some questions based on the above formulae given below:

Question:

At temperature of 298 K the emf of the following electrochemical cell

Ag(s) | Ag+ (0.1 M) | |Zn2+(0.1M) | Zn(s) will be (given Eocell= – 1.562 V)

(a) – 1.532 V

(b) – 1.503 V

(c) 1.532 V

(d) – 3.06 V

Solution:

Question:

Electrolysis of dilute aqueous NaCl solution was carried out by passing 10 mA current. The time required to liberate 0.01 mole of H2 gas at the cathode is (1 F = 96500 C moP1)

(a) 9.65 × 104 s

(b) 19.3 × 104 s

(c) 28.95 × 104 s

(d) 38.6 × 104 s

Solution:

8. Chemical Kinetics:

Students can find some questions based on the above formulae given below:

Question:

The rate of a reaction doubles when its temperature changes from 300 K to 310 K. Activation energy of such a reaction will be (R= 8.314 JK–1 mol–1 and log 2 = 0.301)                             

(A) 53.6 kJ mol–1                            

(B) 48.6 kJ mol–1

(C) 58.5 kJ mol–1                            

(D) 60.5 kJ mol–1

Solution:

Question:

During nuclear explosion one of the products is 90Sr with half-life of 28.1 yr. If 1 µg of 90Sr was absorbed in the bones of a newly born body instead of calcium, how much of it will remain after 60 yr, if it is not lost metabolically?

(A) 0.184 µg

(B) 0.025 µg

(C) 0.262 µg

(D) 0.228 µg

Solution:

9. Solid State:

Primitive unit cells and their possible variations as centered unit cells are given below:

No. of atoms in unit cells in different possible variation are given below:

The packaging efficiency of different crystal structure is given below:

Students can find some questions based on the above formulae given below:

Question:

Solution:

Question:

Solution:

Most Important Questions for JEE Main & Advanced 2018

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