Which of the following statements is correct regarding order of reaction
 

If rate is given by: rate ${\left.=\mathrm{k}\left[\mathrm{A}{]}^{\mathrm{x}}\right[\mathrm{B}]\right]}^{\mathrm{y}}$
then the order $=\mathrm{x}+\mathrm{y}$.
This order can be a positive, negative no., zero or even fractional. It can be determined only experimentally and does not depend on stoichiometric coefficients of reactants.