Earth and Neutral

Google offers some suggestions to your query: http://www.google.com/#hl=en&q=standard+resistance+earth+neutral&aq=f&aqi=m1&aql=&oq=&gs_rfai=&fp=9fe96f41df588170

depends on the cable used and the lenth.

and where the earth is bonded to the nuetral wire in the installation

It varies depending on local electrical regulations, but should be clearly indicated in your local electrical standards and regulations which (given the likely nature of the question) you should be working to.

As for the standard resistance, it seriously depends on where you take the measurement. A common standard resistance of 0.0 ohms should be present when measuring across the earth-neutral link bar of a residential home switchboard on a MEN electrical system when testing to AS/NZS 3000.

There is NO standard value of resistance between neutral and earth. It can be infinite to ZERO, depending on what you mean. (Dry sand is used in some fuses, just because of its high isolation). Somehow you will need to get some moist earth, a little below the surface.

A generator can be used without grounding or earthing the neutral - .

If you refer to codes, it is different from code to code and also different whether you apply safety fault current switching gear or not, and the set point (value) of these.

Here in our house 7 ohms or less is what the code says.

With very sensitive fault disconnects in some parts of the world 100 ohms and more is allowed. (0.2mA - 0.5 mA).

But with such sensitive gear your loads must have a very good isolation, or they trip.

The standard resistance value between the neutral and earth should be zero

.It accaptable maximum upto 0.4 ohm

<...maximum upto 0.4 ohm...>

Not true for an IT earthing system; it could be megohms!

Can you tell more about IT earthing system.

I don't understand,how it could be megaohms ?

Not every country uses the same earth and protection scheme.

Have a look at the following link as it explains IT (isolated earth) nicely and simply.

http://en.wikipedia.org/wiki/Earthing_system

i take you mean for anti static purposes

It depends upon the method of system earthing. In solid earthing it should ideally be zero.