B. Are produced only by living things
D- seismic waves
Geologists use an indirect method to study Earth's interior. Earthquakes produce seismic waves. Geologists record the seismic waves and study how they travel through Earth.
there are 2 hydrogen atoms.
it is right answer that is option B.
TiO2
since Ti has 2 valence e-
to O's 1
Answer:
Tell students that sometimes when two (or more) substances are mixed together, a change occurs and another substance (or substances) is created. This is called a chemical reaction. Gas may form, heat may be produced, and color may change. These types of changes indicate that a chemical reaction has occurred.