Which statement is true of all rocks? (1) rocks contain organic material. (2) rocks contain fossils. (3) rocks are composed of minerals. (4) rocks are formed in layers.

The correct answer is - (3) Rocks are composed of minerals.

All rocks, sedimentary, igneous, or metamorphic are composed of minerals. The rocks can be composed of only one mineral, or they can be composed from two or more minerals.

The igneous rocks tend to be the ones that are composed of only one mineral. The sedimentary rocks are usually composed of two or more minerals, though there are some that are only from one mineral. The metamorphic rocks are the ones that are always composed of two or more minerals as they are rocks that have undergone a structural change under high pressures and temperatures, and also very often merge with other types of rocks in the process.

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.

because natural gas is colorless, odorless, and tasteless, distributors add mercaptan (a chemical that smells like sulfur) to give natural gas a distinct unpleasant odor (it smells like rotten eggs). they locate the types of rock that are likely to contain natural gas deposits.