Why do people want different kinds of light bulbs?

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

when [oh-] is 10-5  m, and [h3o+] is 10-9  m, the poh is 5 and ph is 9. again in both cases the sum of ph and poh is 14. however, the hydrogen ion concentration is not always going to be equal to exactly 1 x 10 raised to a negative number. for example, we skipped over the value of 2.0 x 10-7.