Question

1. choose all that apply.

which two elements are combined to create sand?.
carbon
silicon
oxygen
hydrogen

1. choose true or false.

compounds and elements can be molecules.
true
false

Explanation:

Question 11

Sand is mainly composed of silicon dioxide ($\ce{SiO_2}$), which is a compound of silicon (Si) and oxygen (O). Carbon and hydrogen are not part of the main composition of sand.

Molecules can be made of elements (e.g., $\ce{O_2}$, $\ce{N_2}$) or compounds (e.g., $\ce{H_2O}$, $\ce{CO_2}$). So compounds and elements can be molecules, making the statement true.

Answer:

B. silicon, C. oxygen

Question 12