Radius and volume of a spherical asteroid in standard form

A small asteroid is modelled as a sphere with a diameter of \(1.2\times10^3\) metres.

1. State the radius of the asteroid, in metres, in standard form.[1]

Its volume, in cubic metres, can be written as \(\pi\left(a\times10^k\right)\), where \(1\leq a<10\) and \(k\in\mathbb{Z}\).

2. Determine \(a\) and \(k\).[3]