Answer:
Mg * ignore the division line
Explanation:
Mg has an atomic number of 12.
14 neutrons + 12 protons = mass number of 26
I think its b. if not sorry but its the one that makes most sense
3AlCl₃
molar mass of aluminum chloride AlCl₃ is 133.33 g/mole
133.33 times 3 is 400
put 3 in front of AlCl₃
https://study.com/academy/lesson/aluminum-chloride-formula-molar-mass-decomposition.htm
do you speak english? just curious?