{
  "quizTitle": "CBSE Class X - Chemical Reactions and Equations",
  "quizCategory": "CBSE Class X",
  "quizSubject": "Chemistry",
  "questions": [
    {
      "questionText": "What type of chemical reaction is represented by 2Mg(s) + O₂(g) → 2MgO(s)?",
      "options": [
        "Decomposition Reaction",
        "Combination Reaction",
        "Displacement Reaction",
        "Double Displacement Reaction"
      ],
      "correctOptionIndex": 1,
      "explanationText": "A combination reaction is one where two or more reactants combine to form a single product. Here, magnesium and oxygen combine to produce magnesium oxide.",
      "hint": "Two reactants form a single unified product."
    },
    {
      "questionText": "What observation is made when iron nails are immersed in copper sulfate solution for 20 minutes?",
      "options": [
        "The blue solution turns light green and a brown coating forms on iron nails",
        "The blue solution turns colorless and white gas is evolved",
        "No reaction takes place because copper is more reactive than iron",
        "The iron nail dissolves completely with an explosion"
      ],
      "correctOptionIndex": 0,
      "explanationText": "Iron is more reactive than copper in the reactivity series. Iron displaces copper, forming green ferrous sulfate (FeSO₄) solution and depositing reddish-brown copper on the nails.",
      "hint": "Iron displaces copper from CuSO₄, turning the solution green."
    },
    {
      "questionText": "Which substance is oxidized in the reaction: CuO + H₂ → Cu + H₂O?",
      "options": [
        "CuO",
        "H₂",
        "Cu",
        "H₂O"
      ],
      "correctOptionIndex": 1,
      "explanationText": "Oxidation is the gain of oxygen or loss of electrons/hydrogen. Hydrogen (H₂) gains oxygen to become H₂O, so H₂ is oxidized while CuO is reduced.",
      "hint": "Look at which reactant gains oxygen atoms."
    },
    {
      "questionText": "Why is respiration considered an exothermic process?",
      "options": [
        "Because oxygen is absorbed by blood cells",
        "Because glucose combines with oxygen in cells releasing energy",
        "Because heat is absorbed from the digestive tract",
        "Because carbon dioxide is consumed during breathing"
      ],
      "correctOptionIndex": 1,
      "explanationText": "During digestion, food is broken down into glucose. In our cells, glucose combines with oxygen releasing energy (ATP) along with CO₂ and H₂O, making it exothermic.",
      "hint": "Energy is released when glucose is broken down with oxygen."
    }
  ]
}