Final answer:
To make a buffer solution from 0.10 mol L-1 aqueous NH3, you would need a solution containing its conjugate acid. Among the options listed, E. 0.20 mol L-1 NH4Cl contains the conjugate acid NH4+ and thus will create a buffer with NH3.
Step-by-step explanation:
The question asks which aqueous solution, when mixed with an equal volume of 0.10 mol L-1 aqueous NH3, will produce a buffer solution. A buffer solution can be created by mixing a weak acid with its conjugate base, or a weak base with its conjugate acid. In this case, NH3 is a weak base that can form a buffer solution when mixed with its conjugate acid, which is NH4+. Of the options provided, NH4Cl contains the conjugate acid NH4+ and will form a buffer with NH3. Therefore, the answer is E. 0.20 mol L-1 NH4Cl.