It depends on the density of the material.
It would weigh about 14.3 pounds .
1 ounce
400g
20g
A steel plate of that size would weigh approximately 368 pounds.
depends on how thick the material is . 2 lbs at most
It depends on how thick they are. But a telephone book 1 1/2" thick, weighs 2.5 lbs.
Mac book air weight is 2.3pound (1.06kg)
12 pounds (5.4 kg).
2.54 lbs.
A half inch thick tempered glass will weigh 6.75 lb/ft2. With that much thickness, it can support much of the weight of possibly a small child or small animal.