Verified Answer :

April756

FeS- iron sulfide
NaCl- sodium chloride 
NaOH- sodium hydroxide 
Pb(CN)2- lead cyanide 
They all end in the suffix -ide. 

Dejanras

Answer is: a) -ide.

1) FeS is iron(II) sulfide. Iron has oxidation number +2 and sulfur has oxidation number -2.

2) NaCl is sodium chloride. Sodium has oxidation number +1 and chlorine has oxidation number -1. Sodium cholride is ionic compound, salt.  

3) NaOH is sodium hydroxide. Hydroxide group has negative charge.

4) Pb(CN)₂ is lead(II) cyanide. Lead has oxidation number +2.