Which one is easy to hold in hand, a glass sheet or a cardboard? give reason

Opaque materials are those objects which does not allow light to pass through them. Example: - Wooden board, umbrella.

Transparent materials are those objects which allow light to pass through them in straight lines. As a result we can see the objects clearly. Example: - Plane mirror, water.

Translucent materials are those which let some light to pass through them, the light rays get scatter in all directions, so cannot see clearly through them. Example: - Fog, smoke.

Luminous objects are those which emit light on their own. Example:-Sun, firefly.

Non-luminous objects are those which reflect the light from luminous bodies. Example: - Moon, mirror.

Based on the above definitions we can classify the objects as opaque, transparent, translucent, luminous and non-luminous.

Opaque:  A piece of rock, a sheet of aluminium, 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.

Translucent: A sheet of polythene, smoke, fog, a sheet of cellophane, a wire mesh.

Luminous: A piece of red hot iron, a lighted fluorescent tube, the flame of a gas burner, a lighted torch, sun, firefly, kerosene stove.

Non – luminous: Air, water, a piece of rock, a sheet of aluminium, 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, kerosene stove, moon.

i think the answer is a, hope this is right, that would be my best guess.

im sorry i dont know