PREPTIME

  QUESTIONS AND ANSWERS:  Q25: How is hydrogen gas prepared in the laboratory, and how is it tested?   A25: Preparation Equation : Mg (s) + 2HCl (aq) → MgCl 2 (aq) + H 2 (g) or Zn (s) + 2HCl (aq) → ZnCl 2 (aq) + H 2 (g) or Zn (s) + H 2 SO 4 (aq) → ZnSO 4 (aq) + H 2 (g). Process : Reacting metals like zinc granules or magnesium ribbon with dilute hydrochloric acid or sulphuric acid in a conical flask, collecting the gas by displacement of water. Test : Put a burning/lighted splint in the gas; a “pop” sound indicates the presence of hydrogen gas . Drying : Pass the gas through anhydrous CaCl 2 . Q26: What are the physical and chemical properties of hydrogen gas, and what are its uses?   A26: Physical properties : Lightest gas, lowest density, colourless, odourless, insoluble in water. Chemical properties : Neutral to litmus, unreactive under normal conditions, does not support combustion, burns in ox...

 QUESTIONS AND ANSWERS:  Q12: How do changes of state occur according to the kinetic theory?   A12: Melting : When solids are heated, particles gain kinetic energy and vibrate more strongly. Attractive forces weaken, and particles become free to move around. Freezing : When liquids are cooled, particles lose kinetic energy. Attractive forces strengthen, causing particles to be restricted to a fixed position, moving only by vibration. Evaporation : Occurs when surface particles of a liquid gain enough kinetic energy to move faster and break away from intermolecular forces to form a vapour. Boiling : Rapid vaporisation anywhere in the bulk liquid at a fixed temperature (the boiling point). Condensation : The change from gaseous to liquid form when gas particles lose enough kinetic energy to form bonds and transition into a liquid, the reverse of vaporisation. Q13: What is a 'Gas Law'?   A13: A Gas Law is a mat...

QUESTIONS AND ANSWERS:   Q1: What is the fundamental concept of the kinetic theory of matter?   A1: The kinetic theory of matter is a fundamental concept in chemistry that explains how different states of matter behave. It is based on the idea that matter is made up of tiny particles—molecules, atoms, or ions—that are always in motion. Q2: What are the core statements of the kinetic theory of matter?   A2: The kinetic theory of matter states that: Matter is made of tiny particles which are in constant random motion. Matter possesses kinetic energy due to the motion of the particles. The difference between the different states of matter is due to the nature and extent of motion and the separation between the particles. Q3: What are 'particles' in the context of matter?   A3: Particles are small constituent units of matter, which can be atoms, molecules, or ions. Q4: What are 'intermolecular forces'?   A4: Intermolecular force...

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