Time left 1 The two elements that are frequently used for making transistors are boron and aluminium silicon and germanium iridium and tungsten niobium and columbium 2 Actinides are the elements with atomic numbers from 97 to 104 101 to 115 89 to 103 36 from 43 3 What is laughing gas? Nitrous Oxide Carbon monoxide Sulphur dioxide Hydrogen peroxide 4 From which mineral is radium obtained? Rutile Haematite Limestone Pitchblende 5 Which of the following are the ingredients of gun metal? Iron, Zinc, Titanium Iron, tin Iron, Brass, Tin Copper, Tin 6 Sodium metal is kept under petrol alcohol water kerosene 7 The filament of an electric bulb is made of tungsten nichrome graphite iron 8 Which of the following is in liquid form at room temperature? Lithium Sodium Francium Cerium
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