Time left 1 The element common to all acids is hydrogen carbon sulphur oxygen 2 The chemical (ethyl mercaptan) added to the otherwise odourless LPG cooking gas for imparting a detectable smell to the gas is a compound of bromine fluorine chlorine sulphur 3 Heavy water is deuterium oxide PH7 rain water tritium oxide 4 The group of metals Fe, Co, Ni may best called as transition metals main group metals alkali metals rare metals 5 Among the various allotropes of carbon, coke is the hardest, graphite is the softest diamond is the hardest, coke is the softest diamond is the hardest, graphite is the softest diamond is the hardest, lamp black is the softest 6 Galvanised iron sheets have a coating of lead chromium zinc tin 7 Non stick cooking utensils are coated with Teflon PVC black paint polystyrene 8 When an iron nail gets rusted, iron oxide is formed without any change in the weight of the nail with decrease in the weight of the nail with increase in the weight of the nail without any change in colour or weight of the nail
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