Physics - Solid State Physics - Superconductivity - Zero Resistance: Too Good to Be True?

Scenario: 'In 1911, Onnes cooled mercury to 4.2 K and measured its resistance. He expected it to decrease gradually. Instead, at exactly 4.2 K, resistance DROPPED TO ZERO. Not small - ZERO!' Question 1: 'What would happen if you started a current flowing in a superconducting ring?' A) It would slow