i did a IQ test and got a low number, so i am useless for chess

There is some truth to what you're saying, as there is not a lot of depth (arguably) until you specialize in your field. When I was in chemistry graduate school, my research would be so hyper focused and niche in a specific subject, your goal is to become the worlds best in a specific research field. This requires less broad knowledge and very in depth knowledge. The reason chemistry graduate school would generally be considered easier would be because you have less broad things to learn. 

I see.

Intelligence isn't the only predictor for how good a potential employee will be. It makes sense not to ask about IQ test scores, and it makes sense to not brag about them (or relate them to chess) either.

While I completely agree with Hawking that people often overestimate value of IQ and that there seems to be a cuasality between people who don't have other achievements and people who brag about their IQ, often people also underestimate or missunderstand what IQ test can tell. It does work as a blunt tool to show your potential and your rough ceiling level for what you can do (If you got 90 IQ under normal conditions, I pray to god you're the most diligent student if you wish to finish medical or engineering) but you often need conscientiousness to fullfill your potential. 

And degree from medical school or degree and good grades from law or engineering are better at showing those qualities. You probably smart and hard working enough, especially if you could maintain some level of social life and hobbies while studying. While Mensa membership card just tells that you aced one test one time in your life.

I'll +1 to this.

I think it's more to do with: do you find chess interesting or like chess?  If you put your time into studying lessons/solving puzzles and learning your mistakes after playing a game, you are going to improve (you can say that about other things in life as well).  I got a relatively high score on the Norway mensa test (even though I came to realize that any iq test could not possibly measure your intelligence fully or put it down to a correct number).

As for me, I don't find chess interesting and I don't like chess that much.

Nah i did horrible in the iq test and I’m sure other people have done and are good at chess

     IQ means the ability to discern and quickly and accurately evaluate certain types of puzzles and problems. It does NOT mean those with high scores will learn more, be more competent, understand anything more deeply and thoroughly than others, or be a great success in life or chess.

     Intelligence, and especially the narrow spectrum of it that IQ tests measure, is not a primary ingredient in chess talent. Visualization and visual memory are far more important. Let a GM look at a chess position for 30 seconds, then give him a record of the next eight or ten moves and he will be able to accurately set up the final position on an empty board most of the time. Most of the rest of us will fail. Ask Kasparov about a move he made in a game twenty years ago and he will remember the position. Most of the rest of us will have no clue if asked a similar question.

     So just because your IQ may be average or a bit low there is no reason that you cannot become a very strong chess player.

     Incidentally, those "Carlsen has an IQ of 190" or, earlier, "Kasparov has an IQ of 190" stories come from websites that paid them to take a quick online test and then use their names in ads to get suckers to pay to take those meaningless online tests.

I think they're unrelated, for the most part. Chess ability comes, mainly, from learning and repetition.

I also believe that IQ tests are a dubious way to accurately measure one's general intelligence. Especially the online ones, which put such an emphasis on visual pattern recognition.

An SAT (Scholastic Aptitude Test) is far superior, in my opinion. Though even that falls short, as it still misses out on some key facets of real-world intelligence (such as emotional intelligence, social intelligence, and so on).

In short: I don't think online IQ tests have much value at all, other than being a fun diversion.

     First: quick IQ tests, especially online for-profit websites, are indeed worthless.

     Second: no one who designs, administers, and/or evaluates IQ tests claims that they measure general intelligence, only the capacity for some sorts of learning. SAT tests measure acquired knowledge, not aptitude.

     Third: IQ is one small part of chess talent. It does help to have a good IQ to learn more quickly. Not all that important. There is undoubtedly some innate abilities involved in chess talent, as people such as Morphy, Capablanca, Reshevsky were strong masters within a very shot time without a lot of training. Carlsen shot up to great heights within a relatively short time once he got some training. Certainly these players spent little time on repetition and rote learning.

     IQ bears no strict correspondence to chess talent but does play a minor part.