Below are some puzzles you need to solve to make a 4 letter word.
I am the most important element in your surrounding.
I was found by a Scottish physician.
Who am I?
I am made up of 3 digits.
When you add the digits in me you will get a total of 11 and when you multiply the digits in me you get 9.
My all digits are less then 10 and last digit is divisible by 3.
What number am I?
When you have solved the above puzzles you will get some numbers and letters. Decode them, and you will get the required word.
You can decode them in any order. After decoding you need to rearrange them to get the required word.
Out of three puzzles, one puzzle will give you 2 identical letters.
This is a puzzle of the form '105:315::35:?', i.e. '105 is to 315 as 35 is to ?' In this case, we see that we get 315 by tripling 105; do the same to 35 and we get the answer 105. Note that the value of ASCII-105 is the letter 'I'.
As noted by @ShavinshSharma, this describes Nitrogen, a gas first discovered and isolated by the Scottish physician Daniel Rutherford in 1772 (source: Wikipedia). A nitrogen molecule is written as 'N2' i.e. we need two copies of the letter 'N'.
The result of the mathematics here is the number 119. Note that the value of ASCII-119 is the letter 'W'.
Putting it all together:
We have the four letters I, N, N and W.
If we apply rot-13 to these letters (shift them 13 places in the alphabet) we get the letters V, A, A and J.
This gives us an anagram of the word 'JAVA', which - as a check of the OP's profile page will tell you - is their 'favourite programming language', thus satisfying the title! (Note that @Rand'alThor had already made the same leap here, although I believe this answer now fully describes the logic behind the puzzle...)