Which element is found in all of the following: iron oxide, air, milk, and glass? a) carbon b) hydrogen c) oxygen d) silicon

I believe it is b) hydrogen if that helps

what is the volume occupied by 40 grams of argon gas (ar) at standard conditions? what volume, in liters, is occupied by 1.5 x 1023 

plants need sunlight, water, and carbon dioxide to make food. plants use the raw materials of water, nutrients they absorb from soil, and carbon dioxide to make sugars the plant can use. energy from the sun and chlorophyll are also needed.