A. 1
B. 4
C. 5
D. 3
E. 2
The correct answer is E. 2
The answer is B, you just check if it is the same on the left and right side
A:
Left side - Right side
2xH - 2xH
1xS - 3xS
4xO - 12xO
2xAl - 2xAl
Therefore A is not correct
B:
Left side - right side
2xK - 2xK
1xCl - 1xCl
1xPb - 1xPb
2xN - 2xN
6xO - 6xO
B is therefore correct as both sides add up
