Empirical Formula of a Compound

Give the empirical formula of acetic acid $\left({\mathrm{CH}}_3\mathrm{COOH}\right)$.

Give the empirical formula of acetylene $\left({\mathrm{C}}_2{\mathrm{H}}_2\right)$.

Give the empirical formula of glucose $\left({\mathrm{C}}_6{\mathrm{H}}_{12}{\mathrm{O}}_6\right)$.  

Give the empirical formula of benzene $\left({\mathrm{C}}_6{\mathrm{H}}_6\right)$.