Most of the time, combustion reactions occur when hydrocarbons react with what element? a. sulfur b. oxygen c. chlorine d. nitrogen

When light strikes a plane mirror, images form in locations where light does not actually reach. it only appears to the observer as though the light were coming from this position. what type of image is formed?

What is the result of multiplying (2.5 × 1010) × (2.0 × 10-7)? a. 5.0 × 103 b. 5.0 × 10-3 c. 5.0 × 1017 d. 5.0 × 10-17

All cells are made of four types of acids, lipids, proteins, and carbohydrates.