Set/extend List length in c#

Question

Given a List in c# is there a way to extend it (within its capacity) and set the new elements to null? I\'d like something that works like

Answer 1

Why do you want to do that ? The main advantage of a List is that it can grow as needed, so why do you want to add a number of null or default elements to it ?

Isn't it better that you use an array in this case ?