Mass cannot be used as a property to identidy a sample of matter because it is an extensive property which depends on the amount of matter in a sample, not the tupe of matter it is.
LED bulbs fit standard light sockets and are the most energy-efficient option. LEDs have lower wattage than incandescent bulbs but emit the same light output. This allows them to produce the same amount of light but use less energy. LEDs can last over 20 years and don't contain mercury
