Define $1\, kg$ weight and express it in newton.

It is said that the mass of an object remains constant at all places,while its weight may change. Why?

Why does a body weigh more at the poles than at the equator?

If the diameter of the earth becomes two times its present value and its mass remains unchanged,then how would the weight of an object on the surface of the earth be affected?

An object has a mass of $30 \ kg$. What is its weight $(i)$ on the moon $(ii)$ on another planet? The value of $g$ on the moon is $1/6$ the value of $g$ on the earth. The value of $g$ on the planet is $3$ times the value of $g$ on the earth. Take $g_{earth} = 10 \ m/s^2$.

How does the weight of an object vary with respect to the mass and radius of the Earth? In a hypothetical case,if the diameter of the Earth becomes half of its present value and its mass becomes four times its present value,then how would the weight of any object on the surface of the Earth be affected?