GENERAL KNOWLEDGE: What is an old word for the letter Z?

Questions

For what principal purpose are UHF radio waves used?

Four European countries keep Greenwich Mean Time. The UK and Ireland are two, name either of the others?

Which animal has breeds called Briards and Griffons?

Whose novels include 'The Cement Garden' and 'Comfort of Stangers'?

Dolores Ibarruri was better known under what name during the Spanish Civil War?