Calcium metal reacts with fluorine gas to form solid calcium fluoride. When the reaction is balanced, what coefficient is in front of fluorine gas? A. 1
B. 2
C. 7
D. 3

B= 2

Explanation:

Chemical equation:

Ca + F      →   CaF₂  

Balance chemical equation:

Ca + 2F      →   CaF₂  

Step 1:

Ca + F      →   CaF₂

Left hand side             right hand side

Ca = 1                             Ca = 1

F = 1                                F = 2

Step 2:

Ca + 2F      →   CaF₂

Left hand side             right hand side

Ca = 1                             Ca = 1

F =  2                              F = 2

carbon is a -4 anion

Explanation:

It needs 4 electrons from other molecule(s)/element(s) to be stable.