Good efforts..
>The second most abundant metal found in earth's crust is silicon. Here is the sequence of 9 elements which account for most of the matter found in earth's crust:
oxygen, silicon, aluminium, iron, calcium, sodium, potassium, magnesium, and hydrogen. out of them the non-metal elements are oxygen and hydrogen.

>Charcoal is made by animals' bones.

>when ice melts its density decreases. because density is a mass per unit area(volume). water in ice state has contracted volume and its mass per area is greater but when it melts it starts to expand, thereby its mass per unit area decrease.