__Fe + ___ Cl2 --> ___FeCl3 The coefficient on iron for this equation is:

A 4
B 2
C 1
D 3

Reaction rate depends on how many molecules are coming into contact with each other with enough energy to react. increasing the temperature of the reactants will increase -

Why is the melting of ice a physical change ?

Rank the four gases (air, exhaled air, gas produced from from decomposition of h2o2, gas from decomposition of nahco3) in order of increasing concentration of co2