I have some mosfets that turn on without any voltage applied to the gate, they turn on even without the gate connected to the circuit, I test them in a simple switch circuit using LED, the picture below. also I checked them with the multimeter it gives reading only between the source and the drain, the current flow only from the source to the drain. this is the part numbers. k2519, k1985, k3115, 2d0n60f, irf740, and there is many others with the same problem. I have checked all of its datasheet, it says that they are n channel mosfets, so I don't know what is the problem.

Here you can see the LED is on without the gate even connected (the green wire), (the orange wire is the drain), (the blue wire is the source).