{
  "title": "Questions Set 2",   
  "properties": {     
    "america_discovered_in": {
     "title": "In what year did Christopher Columbus reach the America?",
     "type": "number",
     "oneOf": [
        {
          "type": "number",
          "const": 1420,
          "title": "1420"
        },
        {
          "type": "number",
          "const": 1519,
          "title": "1519"
        },
        {
          "type": "number",
          "const": 1492,
          "title": "1492"
        },
        {
          "type": "number",
          "const": 1607,
          "title": "1607"
        }
      ]
    },
     "symbol_of_water": {
      "title": "What is the chemical symbol for water?",
      "type": "string",
      "oneOf": [
        {
          "const": "H2O",
          "title": "H2O"
        },
        {
          "const": "NaCl",
          "title": "NaCl"
        },
        {
          "const": "O2",
          "title": "O2"
        } ,
        {
          "const": "NH3",
          "title": "NH3"
        } 
      ]
    
    },
     "red_planet": {
      "title": "Which planet is known as the 'Red Planet'?",
      "type": "string",
      "oneOf": [
        {
          "const": "Jupiter",
          "title": "Jupiter"
        },
        {
          "const": "Mars",
          "title": "Mars"
        },
        {
          "const": "Mercury",
          "title": "Mercury"
        },
        {
          "const": "Saturn",
          "title": "Saturn"
        } 
      ]
    },
     "first_president_of_usa": {
      "title": "Who was the first president of the United States?",
      "type": "string",
       "oneOf": [
        {
          "const": "George Washington",
          "title": "George Washington"
        },
        {
          "const": "Abraham Lincoln",
          "title": "Abraham Lincoln"
        },
        {
          "const": "Benjamin Franklin",
          "title": "Benjamin Franklin"
        } 
      ]
    }
  },
  "required": [
      "america_discovered_in",
      "red_planet",
      "symbol_of_water"
    ]
}