How much can a 18-35mm lens zoom in a crop sensor dslr?
In a full frame dslr it is 7.8x as on nikon.com
Nikon's APS-C sensor has a crop-factor of 1.5x
This means that a 18 - 35mm lens is effectively a 27 - 52.5 mm lens when attached to a APS-C DSLR.
Zoom? It does not matter whether it's on crop sensor, in 35mm film or full-frame. 35 divided by 18 is equal to 1.94. The 18-35mm lens is a 1.94X zoom lens every time. I don't know where you got your values and if it really did come from Nikon.
Focal length (18-35mm) does not change too between full-frame and crop sensor but angle of view does. You're using zoom the wrong way. Zoom is nothing more than the ability of the lens to change focal length. It's just that the angle of view a focal length stands for is different between full-frame and crop sensor. That's when you see (35mm film) equivalent values after you multiply the focal length to crop factor (1.5) which would mean the 18-35mm lens on a crop sensor dSLR would behave like a 27-52.5mm lens on a full frame camera. It's just behavior or angle of view.
All those hullabaloo do not tell you how huge a distant object will be using that lens. Here's a quick guide.
A 18-35mm lens is a 1.9x zoom when attached to a full frame camera.
A 18-35mm lens is a 1.9x zoom when attached to a cropped sensor camera.
Nothing magic here. A lens is a lens, no matter if it is used on a DSLR or Cropped camera.