Question

one and of kilos or one and of kilo which is correct why.tell me the reason​

Answer 1

Answer:

The problem is that while mass is the same everywhere on earth, weight is not - it can vary as much as 0.7% from the North Pole (heavy) to the mountains of Peru (light). This is in part caused by the rotation of the earth, and in part by the fact that the earth's surface is not (quite) a sphere.

When you are interested in "how much" of something there is - say, a bag of sugar - you really don't care about the local force of gravity on the bag: you want to know how many cups of coffee you can sweeten with it. Enter the kilogram.