Seven nonmetal elements occur naturally as diatomic molecules: H$_2$, N$_2$, O$_2$, F$_2$, Cl$_2$, Br$_2$, I$_2$
Exercise 1 (Balancing Equations, Single and Double Replacement Reactions)
1. Balance the following equations:
a) __Sb$_2$S$_3$ + __HCl $\rightarrow$ __SbCl$_3$ + __H$_2$S
b) __NaBr + __Ag$_2$SO$_4$ $\rightarrow$ __Na$_2$SO$_4$ + __AgBr
c) __C$_2$H$_6$ + __O$_2$ $\rightarrow$ __CO$_2$ + __H$_2$O