TN 10th Science Master Guide: Important Formulae, Equations & Diagrams

Welcome to the ultimate Class 10 Science Master Guide for the TN Board! 🚀 Scoring a centum in Science requires a balanced preparation strategy across all three branches. You need to quickly recall Physics formulas for numericals, understand Chemistry equations and pH calculations, and draw perfectly labelled Biology diagrams for your 5-mark questions.

To make your revision stress-free and highly effective, we have compiled all the critical formulas, laws, and diagrams into an interactive cheat sheet. Click on the sections below to expand and revise the topics instantly!

💡 Board Exam Presentation Tip:

Physics: Always write the final answer with its correct SI Unit (e.g., Force in $N$, Power in $W$). Missing units will cost you half a mark!

Chemistry: Ensure your chemical equations are balanced and mention the physical states.

Biology: Draw proportional diagrams using a pencil and align all your labels neatly on the right side using a ruler.

📚 Class 10 Science Important Formulae & Diagrams

⚛️ Part 1: Physics - Important Formulae & Laws

Laws of Motion:
- Newton's Second Law: $F = m \times a$ (Force = mass $\times$ acceleration)
- Linear Momentum: $p = m \times v$
- Impulse: $J = F \times t = \Delta p$ (Change in momentum)
Optics:
- Lens Formula: $\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$
- Snell's Law of Refraction: $\frac{\sin i}{\sin r} = \frac{\mu_2}{\mu_1}$
- Power of a Lens: $P = \frac{1}{f}$ (in Dioptre, $D$)
Thermal Physics:
- Ideal Gas Equation: $PV = RT$
- Boyle's Law: At constant temperature, $P \propto \frac{1}{V}$
Electricity:
- Ohm's Law: $V = I \times R$
- Electric Power: $P = V \times I = I^2R = \frac{V^2}{R}$
- Joule's Law of Heating: $H = I^2Rt$
- Resistances in Series: $R_s = R_1 + R_2 + R_3$
- Resistances in Parallel: $\frac{1}{R_p} = \frac{1}{R_1} + \frac{1}{R_2} + \frac{1}{R_3}$
Acoustics (Sound):
- Velocity of sound: $v = n \lambda$ (where $n$ is frequency, $\lambda$ is wavelength)

🧪 Part 2: Chemistry - Important Formulae & Calculations

Atoms and Molecules (Mole Concept):
- Avogadro's Number: $N_A = 6.023 \times 10^{23}$
- Number of moles = $\frac{\text{Mass}}{\text{Atomic Mass / Molecular Mass}}$
- Number of moles = $\frac{\text{Number of Atoms or Molecules}}{\text{Avogadro's Number}}$
- Volume of 1 mole of any gas at STP = $22.4 \text{ Litres}$
Solutions:
- Mass Percentage = $\left( \frac{\text{Mass of Solute}}{\text{Mass of Solution}} \right) \times 100$
- Volume Percentage = $\left( \frac{\text{Volume of Solute}}{\text{Volume of Solution}} \right) \times 100$
Acids, Bases and Salts (pH Calculations):
- $pH = -\log_{10}[H^+]$
- $pOH = -\log_{10}[OH^-]$
- $pH + pOH = 14$
- If $pH < 7$, the solution is acidic. If $pH > 7$, the solution is basic. If $pH = 7$, it is neutral.

🧬 Part 3: Biology - Top 5-Mark Diagrams & Parts

1. Structure of a Typical Angiospermic Ovule (சூல் அமைப்பு)

Question: With a neat labelled diagram, describe the parts of a typical angiospermic ovule.

An angiospermic ovule (also known as a megasporangium) contains the female reproductive cells. The main parts are:

Funiculus: The basal stalk that attaches the ovule to the placenta of the ovary.
Hilum: The junction point where the body of the ovule attaches to the funiculus.
Integuments: The protective outer cell layers surrounding the ovule. Most angiosperms have two layers.
Micropyle: A narrow pore or opening at the tip of the ovule where the integuments are absent. It allows the pollen tube to enter during fertilization.
Chalaza: The basal expanded portion of the ovule situated exactly opposite to the micropylar end.
Nucellus: The central mass of parenchymatous tissue enclosed by the integuments.
Embryo Sac (Female Gametophyte): Located deep within the nucellus, containing the egg apparatus, central cell, and antipodal cells.