K2S (aq) + CoCl2( aq) -----> 2KCl (aq) + CoS (s)
potassium + cobalt potassium chloride + carbonyl sulfide
sulfide chloride
carbonyl sulfide :- it is chemical compound with linear formula (OCS ) normally written as (CoS) .it does not show its structure . its is colorless flammable gas with an unpleasant odour.
Potassium chloride :- It is metal halide salt composed of potassium and chlorine. it is odorless and has white or colorless crystal appearance <span />
Density is the ratio of mass to the volume.
The mathematical expression is given as:

Now, density of isooctane = 
Volume = 
Since, 1 gallon = 3.78 L
So, 3.8 gal = 
= 
As, 1 L = 1000 mL
Therefore,
= 
Volume in mL = 
Put the values,


= 
Hence, mass of 3.8 gal of the gasoline is
.
Answer:
NaOH(aq) + HNO3(aq)------>NaNO3(aq) + H2O(l)
Explanation:
A thing to note is that an acid and a base will react to form a metal salt + H2O.
~Hope it helps:).