Introduction to Chemistry MCQs — Class 6 Science

Introduction to Chemistry | NCERT CBSE Curriculum

Practice 100+ MCQs on Introduction to Chemistry for Class 6 Science. Covers history of chemistry, alchemy, famous scientists, chemical products, and real-world applications - with instant answers and performance report.

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Quick Revision: Introduction to Chemistry

  • What is Science? Science is the systematic ongoing effort by human beings to study, understand and utilize nature through observation and experimentation.
  • What is Chemistry? Chemistry is the branch of science that deals with the study of the composition and physical/chemical properties of matter.
  • Early Discoveries: Early humans learned that cooking over fire makes food tastier; they observed seeds growing into plants and learned agriculture.
  • Alchemy: An ancient practice (from Greek Khemeia = art of transmuting metals) aimed at finding the philosopher's stone to turn base metals into gold.
  • Father of Modern Chemistry: Robert William Boyle — first to perform experiments under controlled conditions, separating Chemistry from Alchemy.
  • John Dalton: Proved that all matter consists of tiny particles called atoms and proposed the Atomic Theory (1766–1844).
  • Antoine Lavoisier: Named carbon, hydrogen, oxygen; discovered oxygen's role in respiration and combustion; established water as a compound.
  • Dmitri Mendeleev: Formulated the Periodic Law and created the Periodic Table of Elements (1834–1907).
  • Marie Curie: Discovered the radioactive metal radium; only person to win the Nobel Prize twice (Physics & Chemistry).
  • Alfred Nobel: Swedish chemist who invented dynamite (1867) and established the Nobel Prizes.
  • Agricultural Chemistry: Fertilisers (urea, ammonium phosphate), insecticides (DDT, BHC), fungicides (Bordeaux mixture), pesticides (Aldrin).
  • Food Chemistry: Preservatives (sodium benzoate, sodium metabisulphite, common salt, sugar) prevent decomposition in jams, pickles, tinned food.
  • Textile Chemistry: Chemistry converts fibres into fabrics; synthetic fibres like nylon, spandex, polyester are strong, wrinkle-resistant, and quick-drying.
  • Medicinal Chemistry: Antibiotics (penicillin, tetracyclin) kill germs; Analgesics (aspirin, paracetamol) relieve pain; Antiseptics fight infection.
  • Fuels & Energy: LPG (cooking), CNG (automobiles), petrol/diesel/kerosene/paraffin wax from petroleum refining. Alternative sources: solar, biogas, ocean energy.
  • Building Materials: Cement, mortar, paints, varnishes, and glass are products of chemistry used in construction.
  • Human Body as Chemical Factory: Uses enzymes for digestion, hormones for controlling vital activities, and hydrochloric acid in the stomach.
  • Dark Side of Chemistry: Chemical weapons (mustard gas, phosgene), explosives (TNT, RDX), harmful addictive drugs (cocaine, heroin).
  • Indian Contributions: Iron pillar near Qutab Minar (rust-resistant due to phosphorus); Acharya P.C. Ray founded India's first pharmaceutical company.
  • Key Discoverers: Joseph Priestly (oxygen), Daniel Rutherford (nitrogen), Henry Cavendish (hydrogen & CO₂), Sir Humphry Davy (potassium & sodium), William Ramsay (inert gases).

Chapter Summary: Introduction to Chemistry

Chemistry is the branch of science that studies the composition, properties, and transformations of matter. It originated from the ancient practice of alchemy, where practitioners sought the philosopher's stone to transmute base metals into gold. Pioneers like Robert Boyle (Father of Modern Chemistry), John Dalton (Atomic Theory), Antoine Lavoisier (role of oxygen, water as a compound), Dmitri Mendeleev (Periodic Table), and Marie Curie (discovery of radium) transformed chemistry into a modern scientific discipline. Indian alchemists contributed through Ayurvedic medicines, and Acharya P.C. Ray established India's first pharmaceutical company.

Today, chemistry plays a vital role in everyday life — from chemical fertilisers (urea, ammonium phosphate) and pesticides (DDT, BHC) that boost food production, to food preservatives (sodium benzoate, salt, sugar) that keep food fresh, and synthetic fibres (nylon, spandex) in the textile industry. Medicines including antibiotics (penicillin), analgesics (aspirin), and antiseptics help fight diseases. Fuels like LPG, CNG, and petroleum products power our homes and vehicles. The "dark side" includes chemical weapons, explosives (TNT, RDX), and harmful drugs. Alternative energy sources such as biogas, solar, and ocean energy are being developed to conserve natural resources for future generations.

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