what factor determines that an oxygen atom can form two covalent bonds while carbon atom can form four

Match each description to the appropriate biome. tropical savanna desert tropical rain forest taiga tundra has sparse vegetation and very cold temperatures located near the equator and contains trees that form dense canopy layers is very hot and dry, and has plants that need little water has cold winters, heavy snowfall and is dominated by conifers has warm temperatures and is dominated by grasses

How many major plates cover the earth

What terms describes being out of water after being submerged