Which element is most important for adding strength to hair, feathers, and outer skin? oxygen hydrogen sulfur phosphorus

Iron reacts with oxygen to produce iron oxide (rust). this reaction is represented in an equation as 4fe + xo2 → 2fe2o3. identify the value of x that will balance the equation.

Food contains a sugar called ( ), which is broken down in a process called cellular ( ). this process uses ( ) to break down food molecules and provide energy for cells. fill in the parentheses

In each transformation of energy , some energy what?