IQ is a relatively stable attribute after adolescence. it begins declining around 60. http://www.oecd-ilibrary.org/education/ageing-and-skills_5k9...

IQ is meant to measure g, or 'general intelligence'. it's roughly the ability to solve complex tasks, and tends to span across domains (ie, if you are above average in one area of problem-solving, you are likely to be above average in others): https://en.wikipedia.org/wiki/G_factor_(psychometrics)

>While at it, show me an IQ test that was compiled using my first language since you are dismissing facts I put on the table.

just for instance: https://en.wikipedia.org/wiki/Raven%27s_Progressive_Matrices