Fill in the blanks with suitable words:
1. Diameter of a circle is _______ its radius.
2. Radius of a circle is ______ its diameter.
3. The diameters of a circle intersect at the ______.
4. The chord passing through the centre of a circle is _________.
5. The biggest chord of a circle is ______.
6. The lengths of the radii of a circle are _______.