Roman emperors
US presidents since 1980
Strings on a guitar
Age of the youngest marathon runner
Days of the week
Continents
Nations who have reached the Rugby World Cup final
Snow White's dwarves
Bottom left button on numeric keypads
Colours of the rainbow
Protons in a nitrogen atom
Brains in a cockroach
Breath-holding record in minutes
Deadly sins
Vertices on a heptagon
Giraffe height in metres
Country names ending in "TAN"
Voyager 1's distance from Earth in light years
Wonders of the ancient world
September
Countries which border Iran
XII
Husbands of Elizabeth Taylor
Digit in James Bond's codename
Power of the largest-ever H-bomb in megatons
Members of the Fellowship of the Ring
Countries with both Pacific and Caribbean coastlines
BC century in which the Persian Empire emerged
Baby rabbits in an average litter
Welsh cities
Galaxies in the local group
Cristiano Ronaldo's number
FA Cup winning teams from London
Notes in a major scale
Emirates in the UAE
Average yardage lost in an NFL sack
Countries that start with P
Spikes on the Statue of Liberty's crown
Byzantine emperors named Constantine
Antarctic bases
Fights Mike Tyson lost
Japanese car manufacturers in the top 20
Alpine salamanders' gestation period in months
Altitude in miles at which the stratosphere starts
Magnificent characters in the famous western
Typical snail speed in metres per hour
Speed of the fastest spaceship in mach
Diameter in feet of the largest wheels on a vehicle