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