/6 Science Quiz (for 12 to 16 years old): Quiz 17 1 / 6Quartz crystals normally used in quartz clocks etc. is chemically germanium oxide sodium silicate a mixture of germanium oxide and silicon dioxide silicon dioxide 2 / 6The gas usually filled in the electric bulb is nitrogen hydrogen oxygen carbon dioxide 3 / 6Chlorophyll is a naturally occurring chelate compound in which central metal is magnesium calcium iron copper 4 / 6Heavy water is deuterium oxide rain water tritium oxide PH7 5 / 6Carbon, diamond and graphite are together called allotropes isomorphs isotopes isomers 6 / 6Washing soda is the common name for Calcium bicarbonate Calcium carbonate Sodium carbonate Sodium bicarbonate Your score is 0% Restart quiz Next quiz Please rate the quiz Send feedback By WordPress Quiz plugin