Classify the objects or materials given below as opaque, transparent or translucent and luminous or non-luminous:
Air, water, a piece of rock, a sheet of aluminium, a mirror, a wooden board, a CD, smoke, a sheet of plain glass, fog, a piece of red-hot iron, an umbrella, a lighted fluorescent tube, a wall, a sheet of carbon paper, the flame of a gas burner, a sheet of cardboard, a lighted torch, a sheet of cellophane, a wire mesh, kerosene stove, Sun, firefly, moon. [5 MARKS]
Each Point: 1 Mark
Opaque: a piece of rock, a sheet of aluminum, a mirror, a wooden board, a CD, an umbrella, a wall, a sheet of carbon paper, a sheet of cardboard.
Transparent: Air, water, a sheet of plane glass, a sheet of cellophane.
Translucent: smoke, fog, a wire mesh.
Luminous: a piece of red-hot iron, a lighted fluorescent tube, the flame of a gas burner, a lighted torch, kerosene stove, Sun, firefly.
Non-luminous: Air, water, a piece of rock, a sheet of aluminum, a mirror, a wooden board, a sheet of polythene, a CD, smoke, a sheet of plane glass, fog, an umbrella, a wall, a sheet of carbon paper, a sheet of cardboard, a sheet of cellophane, a wire mesh, moon.