Hockey: One of three 20 minute segments making up the game?

Questions

On which planet, other than earth, did a man made object first land?

On which popular game board would you find 225 squares?

On which scale are there 180 degrees between freezing point & boiling point?

On which subject did Richard Strauss write a 'Gay Viennese Ballet'?

One gram of pcbs can make up to ____________ litres of water unsuitable for freshwater aquatic life?