Misc: What is the geographical term for a ring shaped coral island?

Questions

In 1896, Britain and Zanzibar were at war for _____ minutes?

Numbering houses in London streets only began in?

More than 75% of all the countries in the world are _____ of the equator?

Less than 1% of the ________ Islands are inhabited?

On average, an iceberg weighs __________ tons?