Opposite pairs form ionic bonds, due to this the answer is D - Li and Br; They have unlike charges.
K, ca, sc is the right answer. Take a look at table S of your chemistry reference table.
Cs -137 has a half life of about 30 years. If 60 years pass, there is two half lives passed so 1/2 * 1/2= 1/4. Take 1/4 and multiply it with the mass given:
(1/4)*20mg=5mg left
Answer:
depending on what school you go to and what classes you are allowed to take in which grades, you should take forensics.
