(a) No. The integers are not dense. And the rationals are dense.Originally Posted bysuedenation

(b)No. Because is a commutative ring, while the quaternion numbers are not. Because for example, while

(c)Yes. I really do not see how order is important in a direct product between rings.

(e)No. The reals are ordered but the complex numbers cannot be ordered.

I am thinking about (d)