grammatical number - it was/it were + plural noun

Which of the following is correct?

1. It was the memories he made that mattered.




2. It were the memories he made that mattered.

Answer

Since "it" is singular, here "was" seems more appropriate.
So the right sentence would be:

It was the memories he made that mattered.

"were" is used with singular nouns/pronouns only when the sentence is in the SUBJUNCTIVE mood which is used for hypothetical situations. For example:

If I were you, .....