You are the medical examiner at the scene of a murder at a restaurant. There is a suspicion that the victim was poisoned. Their blood contained the following %
composition 80.66%-c, 7.39%-H, 9.39 %-N, and 2.68%-o Which of the following
compounds was the cause of the murder?

The compound : C₄₀H₄₄N₄O

The empirical formula is the smallest comparison of atoms of compound =mole ratio of the components

The principle of determining empirical formula

•Determine the mass ratio of the constituent elements of the compound.  

•Determine the mole ratio by dividing the percentage by the atomic mass

The mol ratio of composition : C : H : N : O