General Science and Life Science (Class 10 CBSE) — RRB NTPC Study Notes

Overview

General Science forms a crucial component of the General Awareness section in RRB NTPC, accounting for approximately 15-20 questions. This topic covers fundamental concepts from Physics, Chemistry and Biology up to Class 10 CBSE level. The questions test basic scientific principles, definitions, applications and simple numerical problems.

Students must focus on understanding core concepts rather than memorising formulas alone. RRB typically asks direct questions on scientific laws, units, definitions, chemical reactions, human body systems and environmental science. The key to scoring well is maintaining clarity on fundamental principles across all three sciences and their real-world applications, especially those relevant to railways and everyday technology.

A systematic revision of NCERT Class 10 Science textbook chapters, combined with practice of previous year questions, provides the best preparation strategy for this section.

Key Concepts

• **Physics fundamentals**: Light reflection/refraction, electricity (Ohm's law, power, series/parallel circuits), magnetic effects of current, energy sources (renewable/non-renewable), and basic mechanics (force, work, power, energy).

• **Chemical reactions and equations**: Understanding balancing equations, types of reactions (combination, decomposition, displacement, redox), and recognising common chemical formulas of acids, bases and salts.

• **Periodic classification**: Trends in the periodic table (atomic size, metallic character, valency), groups and periods, and properties of metals/non-metals/metalloids.

• **Human physiology**: Functions of major organ systems — digestive, respiratory, circulatory, excretory, nervous and reproductive systems, along with common diseases and preventive measures.

• **Plant biology**: Photosynthesis, respiration, transportation in plants, nutrition modes (autotrophic/heterotrophic), and plant hormone functions.

• **Genetics and evolution**: Mendel's laws, inheritance patterns, DNA structure basics, natural selection, and evidence for evolution (fossils, homologous organs).

• **Environmental science**: Ecosystem components, food chains/webs, ozone layer depletion, greenhouse effect, waste management and biodegradable/non-biodegradable materials.

• **Practical applications**: Understanding how scientific principles apply to railway operations — electrical traction, signalling systems, material strength, energy efficiency and environmental compliance.

Key Facts

**Physics:** • SI unit of electric current: Ampere (A); Resistance: Ohm (Ω); Power: Watt (W); Energy: Joule (J) • Ohm's Law: V = IR (Voltage = Current × Resistance) • Electric Power: P = VI = I²R = V²/R • Laws of reflection: Angle of incidence = Angle of reflection; incident ray, reflected ray and normal lie in same plane • Refractive index: Speed of light in vacuum / Speed of light in medium • Fleming's Left Hand Rule determines direction of force on current-carrying conductor in magnetic field

**Chemistry:** • pH scale: 0-7 (acidic), 7 (neutral), 7-14 (basic) • Common acids: HCl (hydrochloric), H₂SO₄ (sulphuric), HNO₃ (nitric), CH₃COOH (acetic) • Common bases: NaOH (sodium hydroxide), Ca(OH)₂ (calcium hydroxide), NH₄OH (ammonium hydroxide) • Metals react with oxygen to form basic oxides; non-metals form acidic oxides • Down a group: atomic size increases, metallic character increases; Across a period: atomic size decreases, non-metallic character increases

**Biology:** • Photosynthesis equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂ • Respiration equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + energy (ATP) • Human heart: 4 chambers (2 atria, 2 ventricles); double circulation • Nephron: functional unit of kidney; filtration, reabsorption, secretion • Trophic levels: Producers → Primary consumers → Secondary consumers → Tertiary consumers • Ozone formula: O₃; protects from harmful UV radiation

Worked Examples

**Example 1: Electrical Power Calculation** A railway signal operates at 220V and draws a current of 0.5A. Calculate the power consumed and resistance.

*Solution:* Given: V = 220V, I = 0.5A Power P = VI = 220 × 0.5 = 110W Resistance R = V/I = 220/0.5 = 440Ω

**Example 2: Chemical Equation Balancing** Balance the equation: Fe + H₂O → Fe₃O₄ + H₂

*Solution:* Step 1: Count atoms on both sides Step 2: Balance Fe: 3Fe on right, so 3Fe on left Step 3: Balance O: 4O on right, so 4H₂O on left Step 4: Balance H: 8H on left, so 4H₂ on right Balanced equation: 3Fe + 4H₂O → Fe₃O₄ + 4H₂

**Example 3: Food Chain Energy Transfer** If a grassland has 10,000J of energy at producer level, how much energy reaches secondary consumers?

*Solution:* Energy transfer between trophic levels ≈ 10% Producers (10,000J) → Primary consumers (1,000J) → Secondary consumers (100J) Energy reaching secondary consumers = 100J

Common Mistakes

**Mistake 1: Confusing series and parallel circuit properties** Wrong thinking: "Total resistance decreases in series circuits." Correct fix: In series, total resistance R = R₁ + R₂ + R₃ (increases). In parallel, 1/R = 1/R₁ + 1/R₂ + 1/R₃ (decreases).

**Mistake 2: Mixing up acids and bases pH values** Wrong thinking: "Strong acids have high pH values." Correct fix: Strong acids have LOW pH (0-3); strong bases have HIGH pH (11-14). pH 7 is neutral.

**Mistake 3: Reversing photosynthesis and respiration equations** Wrong thinking: "Plants only photosynthesize; animals only respire." Correct fix: Plants do BOTH — photosynthesis during day (using CO₂, releasing O₂) and respiration always (using O₂, releasing CO₂). Animals only respire.

**Mistake 4: Confusing homologous and analogous organs** Wrong thinking: "Wings of birds and insects are homologous because both fly." Correct fix: These are analogous (similar function, different origin). Homologous organs have same origin but may have different functions (forelimbs of humans, whales, bats).

**Mistake 5: Incorrect application of 10% energy law** Wrong thinking: "If producers have 1000J, tertiary consumers get 300J." Correct fix: Each level transfers ~10%. Tertiary consumers are 4th level: 1000 → 100 → 10 → 1J.

Quick Reference

• **Electricity basics**: V = IR; P = VI; Series adds resistance; Parallel reduces resistance • **Light**: Real images are inverted and formed by concave mirrors/convex lenses; Virtual images are erect • **Chemical reactions**: Combination (A+B→AB), Decomposition (AB→A+B), Displacement (A+BC→AC+B), Redox (electron transfer) • **Periodic trends**: Atomic size increases down group, decreases across period; Metallic character increases down, decreases across • **Human systems**: Heart (4 chambers), Lungs (gas exchange), Kidney (filtration), Brain (control centre) • **Energy flow**: Only 10% energy transfers between trophic levels; Rest lost as heat • **Environmental**: CO₂ causes greenhouse effect; CFCs deplete ozone; Biodegradable materials decompose naturally