NTPC ALP Group D

Chemistry for RRB Exams

Matter & Atomic Structure

Subatomic Particles

• Electron: J.J. Thomson (Negative charge)
• Proton: E. Rutherford (Positive charge)
• Neutron: James Chadwick (No charge)
• Atomic Number (Z): Number of protons
• Mass Number (A): Protons + Neutrons
• Isotopes: Same atomic number, different mass number (e.g., C-12, C-14)

Periodic Table

Key Facts

• Modern Periodic Law: Henry Moseley (based on Atomic Number)
• Groups: 18 vertical columns
• Periods: 7 horizontal rows
• Group 1: Alkali Metals
• Group 17: Halogens
• Group 18: Noble Gases (Inert gases)
• Lightest Element: Hydrogen
• Heaviest Naturally Occurring Element: Uranium

Acids, Bases & Salts

pH Scale (0-14)

• Acidic: pH < 7 (Turns blue litmus red)
• Neutral: pH = 7 (Water)
• Basic/Alkaline: pH > 7 (Turns red litmus blue)
• Blood pH: 7.4 (Slightly basic)

Common Chemicals

• Vinegar: Acetic Acid
• Lemon/Orange: Citric Acid
• Curd: Lactic Acid
• Ant Sting: Formic Acid (Methanoic Acid)
• Stomach Acid: Hydrochloric Acid (HCl)
• Baking Soda: Sodium Bicarbonate (NaHCO₃)
• Washing Soda: Sodium Carbonate (Na₂CO₃)

Metals & Non-Metals

Important Facts

• Liquid Metal at room temp: Mercury (Hg)
• Liquid Non-metal: Bromine (Br)
• Best Conductor: Silver (Ag)
• Hardest Natural Substance: Diamond (Carbon allotrope)
• Lightest Metal: Lithium
• Most Abundant Metal in Earth's Crust: Aluminium

Alloys

• Brass: Copper + Zinc
• Bronze: Copper + Tin
• Stainless Steel: Iron + Chromium + Nickel
• Solder: Lead + Tin

Important Compounds

Chemical Formulas

• Common Salt: NaCl
• Bleaching Powder: CaOCl₂
• Plaster of Paris: CaSO₄·½H₂O
• Gypsum: CaSO₄·2H₂O
• Laughing Gas: Nitrous Oxide (N₂O)
• Dry Ice: Solid Carbon Dioxide (CO₂)

Test Your Knowledge

30 random questions • 1 minute per question