What is the main structural component of a plant?

What substance is the most acidic. lemon juice. tomato juice. sodium hydroxide. water

When a gasoline engine burns gasoline, what type of chemical reaction is occurring?

Homo heidelbergensis was a tall, muscular hunter, who used both tools and weapons. because h. heidelbergensis was not a gatherer/forager, but ate a varied diet including meat and fish, we would expect to see what anatomical changes?