Related Clues:

• Bleach compound
• Lightest of all gases
• It's great gas for egg producer admitting dry mixture to go back
• Most abundant substance in the universe
• Chemical element with atomic no. 1 in the periodic table
• Pig swallows dry mixture from scenic centre - it's gas!
• Kind of bomb that, shortly, may be dropped in part of London
• Element supplying hotel with information
• Hotel has information identifying bomb-maker
• End of speech expanded — it's a gas
• Helpfully discover orbiting electron on the outside — of this?
• The commonest element in info on hotel
• An element of greyhound racing that's not upper-class
• Resort data element
• Extremes in heavy drinker, overpowering even, producing gas