Railways General Science Masterclass: 25 High-Frequency Physics, Chemistry & Biology PYQ Concepts
In RRB Group D and RRB NTPC examinations, General Science accounts for 25 to 30 marks of the composite paper. Unlike civil services examinations that emphasize science and technology policy, Railway examinations test fundamental NCERT Class 9 and 10 textbook principles, numerical formulas, and chemical equations.
Analysis of the last 15,000 RRB questions reveals that over 70% of science questions repeat from 25 core foundational archetypes. This masterclass provides the exact concepts, numerical shortcuts, and trap matrices tested by the Railway Recruitment Board.
1. Physics: Essential Formulas & Numerical Traps
A. Optics: Mirror & Lens Sign Conventions
- Mirror Formula: $\frac{1}{f} = \frac{1}{v} + \frac{1}{u}$ | Linear Magnification: $m = -\frac{v}{u} = \frac{h_i}{h_o}$
- Lens Formula: $\frac{1}{f} = \frac{1}{v} - \frac{1}{u}$ | Linear Magnification: $m = +\frac{v}{u} = \frac{h_i}{h_o}$
- Power of a Lens: $P = \frac{1}{f \text{ (in meters)}}$ (Measured in Dioptres, D).
- Convex Lens $\implies f > 0 \implies P$ is Positive (Hypermetropia / Long-sightedness).
- Concave Lens $\implies f < 0 \implies P$ is Negative (Myopia / Short-sightedness).
B. Electricity: Ohm's Law & Resistance Combinations
- Ohm's Law: $V = I R$
- Resistance Formula: $R = \rho \frac{L}{A}$ (If length of wire is doubled and area halved, resistance increases $4\times$).
- Equivalent Resistance:
- Series: $R_{\text{eq}} = R_1 + R_2 + R_3$
- Parallel: $\frac{1}{R_{\text{eq}}} = \frac{1}{R_1} + \frac{1}{R_2} \implies R_{\text{eq}} = \frac{R_1 R_2}{R_1 + R_2}$
- Electric Power: $P = V I = I^2 R = \frac{V^2}{R}$ | Energy consumed in 1 unit $= 1 \text{ kWh} = 3.6 \times 10^6 \text{ Joules}$.
2. Chemistry: Periodic Table Trends & Everyday Compounds
A. Periodic Table Trend Matrix (Modern Periodic Table - Moseley)
| Property | Across a Period (Left to Right) | Down a Group (Top to Bottom) | Reason |
|---|---|---|---|
| Atomic Radius | Decreases | Increases | Increased nuclear charge vs new electron shell added |
| Ionization Energy | Increases | Decreases | Valence electrons held tighter vs farther from nucleus |
| Electronegativity | Increases (Fluorine is max) | Decreases | Non-metallic character increases across period |
| Metallic Character | Decreases | Increases | Tendency to lose electrons increases down group |
B. Frequently Tested Commercial Chemical Formulas
- Bleaching Powder: $\text{CaOCl}_2$ (Calcium oxychloride)
- Baking Soda: $\text{NaHCO}_3$ (Sodium hydrogen carbonate)
- Washing Soda: $\text{Na}_2\text{CO}_3 \cdot 10\text{H}_2\text{O}$ (Sodium carbonate decahydrate)
- Plaster of Paris: $\text{CaSO}_4 \cdot \frac{1}{2}\text{H}_2\text{O}$ (Formed by heating Gypsum $\text{CaSO}_4 \cdot 2\text{H}_2\text{O}$ at 373 K).
- Slaked Lime: $\text{Ca(OH)}_2$ | Quick Lime: $\text{CaO}$
3. Biology: High-Yield Human Physiology & Deficiency Diseases
A. Vitamin Classification & Deficiency Matrix
- Fat-Soluble Vitamins: Vitamins A, D, E, K (Stored in liver and adipose tissue).
- Water-Soluble Vitamins: Vitamins B-Complex and C (Must be supplied regularly in diet).
| Vitamin | Chemical Name | Deficiency Disease | High-Yield Fact |
|---|---|---|---|
| Vitamin A | Retinol | Night Blindness (Nyctalopia), Xerophthalmia | Essential for rhodopsin synthesis |
| Vitamin B1 | Thiamine | Beriberi | Affects cardiovascular and nervous systems |
| Vitamin B3 | Niacin | Pellagra (4D symptoms: Dementia, Diarrhea, Dermatitis, Death) | Synthesized from tryptophan |
| Vitamin B12 | Cyanocobalamin | Pernicious Anemia | Contains cobalt metal ion |
| Vitamin C | Ascorbic Acid | Scurvy (Bleeding gums) | Heat-sensitive; destroys upon cooking |
| Vitamin D | Calciferol | Rickets (Children), Osteomalacia (Adults) | Synthesized in skin via UV light |
| Vitamin K | Phylloquinone | Delayed blood clotting (Hemorrhage) | Essential for prothrombin synthesis |
B. Human Blood Groups & Circulatory Facts
- Universal Donor: $O^-$ (Rh negative) — possesses zero antigens on RBC surface.
- Universal Acceptor: $AB^+$ (Rh positive) — possesses both A and B antigens, zero antibodies in plasma.
- Normal Blood Pressure: 120/80 mm Hg (Systolic / Diastolic). Measured using a Sphygmomanometer.
- pH of Human Blood: 7.35 to 7.45 (Slightly alkaline).
4. Cross-Study Resources & Preparation Links
- Estimate your normalized score on the Railways Score Normalization Calculator.
- Master speed math shortcuts on the RRB Group D Arithmetic & Reasoning Guide.
- Download authentic past 10-year question papers on the Competitive Exam PYQ Archive.
- Take computerized General Science sectional mock drills on the Student CBT Mock Test Engine.
Frequently Asked Questions (FAQ)
Q1: What level of science is asked in RRB Group D and NTPC?
Science questions are framed strictly from Class 9 and Class 10 NCERT textbooks. Memorizing periodic trends, common chemical formulas, lens/mirror sign conventions, and vitamin deficiencies ensures 85%+ score in science.
Q2: How can I avoid negative marking in General Science?
Because RRB enforces a strict 1/3rd penalty, never attempt science questions using 50:50 guesswork. If you cannot definitively recall whether Vitamin C is heat-labile or fat-soluble, leave the question unattempted.