5 High-Scoring States of Matter Tricks for JEE Chemistry

Introduction

States of Matter is one of the easiest scoring chapters in JEE Chemistry—but also one of the easiest places to lose marks because of unit mistakes.

Most questions are formula-based.

The key is knowing the right shortcut and applying it correctly.

Here are 5 quick tricks to solve gas and liquid questions faster.

---

1Use the Two-State Gas Equation

If a gas changes from one condition to another:

$$\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}$$

If moles also change:

$$\frac{P_1V_1}{n_1T_1}=\frac{P_2V_2}{n_2T_2}$$

Shortcut:

No need to calculate (R).

Remember:

Temperature must be in Kelvin.

$K = ^\circ C + 273$

---

2RAM Trick for Gas Speeds

Remember:

R → RMS
A → Average
M → Most probable

Formulas:

$$V_{rms}=\sqrt{\frac{3RT}{M}}$$ $$V_{avg}=\sqrt{\frac{8RT}{\pi M}}$$ $$V_{mp}=\sqrt{\frac{2RT}{M}}$$

Order:

$V_{rms}>V_{avg}>V_{mp}$

Quick memory:

RAM = biggest to smallest.

---

3Understand Van der Waals Constants

Real gas equation:

$$\left(P+\frac{an^2}{V^2}\right)(V-nb)=nRT$$

Easy memory:

a = attraction

Higher (a) means stronger attraction.

b = size

Higher (b) means bigger molecules.

Quick rule:

Low pressure:

$Z<1$

High pressure:

$Z>1$

---

4Graham’s Law Shortcut

Rate of diffusion:

$$\frac{r_1}{r_2}=\sqrt{\frac{M_2}{M_1}}$$

Lighter gas moves faster.

Time relation:

$$\frac{t_1}{t_2}=\sqrt{\frac{M_1}{M_2}}$$

Quick memory:

Rate → inverse

Time → direct

---

5Temperature Effect on Liquids

As temperature increases:

Viscosity decreases.

Surface tension decreases.

At critical temperature:

$\text{Surface tension}=0$

Quick memory:

Temperature up → liquid resistance down.

---

Quick Revision Table

---

Final Tip

In States of Matter, most mistakes happen because of:

• wrong units
• wrong temperature scale
• inverted ratios

Always check units before solving.

That alone can save marks in JEE.