Answer:
A. Elements
Elements are substances that cannot be separated into simpler substances. Salt is made up of the elements sodium and chloride. Water is made up of the elements hydrogen and oxygen, to list a few.
Answer:
The professionals that most likely use X-ray technology are a dentist and an airport-security scanner.
A dentist would scan your teeth using X-ray technology to see whether there are any cavities within the teeth themselves which he couldn't otherwise see with the naked eye. An airport-security scanner would use this technology to scan your luggage to check whether there are any weapons and other illegal products.
Explanation:
Helium used to be used in hot air balloons. Then, when the Hindenburg exploded, annexed file, they realized that hydrogen was not only lighter, but it also was less flammable.
Answer:
pressure
Explanation:
gas convert to liquid at high pressure.
