If 1 January 2012 was on Wednesday, then what was the last day of this year ?

Thursday

In an ordinary year the First and the Last Day of that year are the same.

Whereas, In a leap year to calculate the last day of the year, we need to add one day to the First day of that leap Year

.Now, As, the year given in the question  is a leap year, So, we’ll add one day to Wednesday and that will be Thursday .