I think this is how you do it:
1.2*104 is 12000 it is easy just try ur best
The dermal tissue is basically the outer part of the cell that protects the plant cell so in that case it would be the carbohydrate or cell wall. If you would put the choices it could have been a bit better :)
The law of conservation of mass states that mass is neither created nor destroyed. Since we have 2 g/mol of A and 3 g/mol of B then AB should be equal to the sum of their molar mass that is
2 g/mol + 3 g/mol = 5 g/mol AB
for the case of A2B3
A2 = 2 * 2 = 4 g/mol
B3 = 3 * 3 = 9 g/mol
therefore A2B3 = 13 g/mol