Answer
a. $S_4N_4H_4$
b. $N_3P_3Cl_6$
c. $Co_2C_8O_8$
Work Step by Step
a. $\text{ Molar Mass of $SNH$} =32.065+14.0067+1.00794=47.080\text{ grams}$
$\frac{188.35}{47.080}=4$.
$SNH\Rightarrow S_4N_4H_4$
b. $\text{ Molar Mass of $NPCl_2$} = 14.0067+30.97376+2*35.453=115.886\text{ grams}$
$\frac{347.64}{115.886}=3$.
$NPCl_2\Rightarrow N_3P_3Cl_6$
c. $\text{ Molar Mass of $CoC_4O_4$} =170.9736\text{ grams}$
$\frac{341.94}{170.9736}=2$.
$CoC_4O_4\Rightarrow Co_2C_8O_8$
