Which of the following is not an example of a pulley:
a. blinds in a window
b. ski lift
c. flag pole
d. wheelbarrow

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.

2points what is the term for a female reproductive cell? a. egg b. chromatid c. allele d. fertilization

In what for do plants utilize nitrogen? why do they need nitrogen?