Atablet of benadryl (r), an antihistamine, has a mass of 0.50g. it contains 25 mg of the active ingredient, diphenhydramine hcl. what percent of the tablet is active ingredient? how do i solve this

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6

16

explanation:

the marks go by 4s

metric time was an attempt to create a standard unit of time based off of 10, but it never took off an is not included in the metric system (si)