The process of converting a solid directly into gas without passing through the liquid state is called:
A. Sublimation
B. Fusion
C. Condensation
D. Evaporation
Answer: Option A
Solution (By JKExamLibrary)
Sublimation is the transition of a substance directly from the solid to the gas state without becoming an intermediate liquid. Condensation is gas to liquid, evaporation is liquid to gas at any temperature, and fusion is solid to liquid. Common examples include camphor, naphthalene, and dry ice.
Explanation:
Fractional distillation is used when the boiling points differ by less than 25 K. A fractionating column provides repeated condensation–vaporization cycles, improving separation. Example: separation of petrol, kerosene from crude oil. Simple distillation works if difference > 25 K. Separating funnel separates immiscible liquids. Crystallization purifies solids. Exam note: Fractionating column packed with glass beads increases surface area.
Explanation:
Hydrogen peroxide (H₂O₂) is a strong oxidizing agent that kills microorganisms through oxidative damage and bleaches colored substances. It is used as a disinfectant (3% solution), in hair bleaching, and in the paper textile industry. Ethanol is a disinfectant but not a strong bleaching agent. Methanol is toxic, not used for sterilization. Acetone is a solvent.
Explanation:
John Dalton proposed the atomic theory in 1803. His theory stated that all matter is made of indivisible and indestructible atoms, atoms of a given element are identical in mass and properties, and compounds are formed by combinations of different atoms in fixed ratios.
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