{
  "format": "brainjoy-quiz",
  "version": 1,
  "title": "Particle detectives: atoms, ions and isotopes",
  "subject": "Chemistry",
  "grade": "Secondary introduction",
  "questions": [
    {
      "type": "mcq",
      "text": "Which particle is uncharged?",
      "options": [
        "Proton",
        "Neutron",
        "Electron"
      ],
      "correct": 1
    },
    {
      "type": "short",
      "text": "A neutral carbon atom has 6 protons. How many electrons does it have? Enter digits only.",
      "answer": "6"
    },
    {
      "type": "short",
      "text": "An atom has atomic number 8 and mass number 18. How many neutrons does it have? Enter digits only.",
      "answer": "10"
    },
    {
      "type": "tf",
      "text": "Carbon-12 and carbon-13 have different numbers of protons.",
      "correct": false
    },
    {
      "type": "mcq",
      "text": "An atom has 7 protons and 8 neutrons. What is its mass number?",
      "options": [
        "1",
        "7",
        "8",
        "15"
      ],
      "correct": 3
    },
    {
      "type": "mcq",
      "text": "Which particle number identifies an element?",
      "options": [
        "Proton number",
        "Neutron number",
        "Electron number alone",
        "Protons plus electrons"
      ],
      "correct": 0
    },
    {
      "type": "short",
      "text": "A sodium ion has 11 protons and a charge of +1. How many electrons does it have? Enter digits only.",
      "answer": "10"
    },
    {
      "type": "short",
      "text": "A chloride ion has 17 protons and a charge of -1. How many electrons does it have? Enter digits only.",
      "answer": "18"
    },
    {
      "type": "tf",
      "text": "In ordinary ion formation by electron transfer, the proton number stays the same.",
      "correct": true
    },
    {
      "type": "mcq",
      "text": "Which pair represents isotopes of the same element? Each pair is written as (protons, neutrons).",
      "options": [
        "(6, 6) and (7, 6)",
        "(8, 8) and (8, 10)",
        "(11, 12) and (12, 11)",
        "(3, 4) and (4, 3)"
      ],
      "correct": 1
    },
    {
      "type": "short",
      "text": "A magnesium-24 ion has 12 protons and a charge of +2. How many electrons does it have? Enter digits only.",
      "answer": "10"
    },
    {
      "type": "mcq",
      "text": "A learner says: \"A positive ion has gained positive protons.\" For ordinary ion formation by electron transfer, what is the better explanation?",
      "options": [
        "It lost negative electrons.",
        "It gained negative electrons.",
        "Every neutron became a proton.",
        "Its mass number must become zero."
      ],
      "correct": 0
    }
  ]
}