Words that start with 'i' and contain 'val'

How many words are possible to make using this list?
In total, there are 58 words.

Which word that starts with 'i' and includes 'val' is the most common word in the dictionary?
There's 'intervals', which ranks as the 4222^nd most common word.

What is an example of a interesting word from this page?
You'll notice many strange words in this list, having said that our favorite is 'invalidate'. The definition of 'invalidate' is as follows: "To render invalid; to weaken or lessen the force of; to destroy the authority of; to render of no force or effect; to overthrow; as, to invalidate an agreement or argument.". Source Oxford Dictionary.

What's the highest scoring word in Scrabble available from this list ?
For a score of 12 points in Scrabble, you can play 'invalids'.

How many characters does the longest word from this list contain?
Try 'inequivalvular', which is made up of 14 characters.