Questions

A substance that cannot be decomposed (broken down) into simpler substances by ordinary chemical means.

Examples: gold, iron, carbon, hydrogen, oxygen, nitrogen.

Material composed of only one kind of matter throughout (same atoms or same molecules).

International Firefighters' Day (IFFD) is observed on May 4. It was instituted after proposal emailed out across the world on January 4, 1999 due to the deaths of five firefighters in tragic circumstances in a bushfire in Australia.

1 atm: It was originally defined as the pressure exerted by 760 mm of mercury at 0 °C and standard gravity (g = 9.80665 m/s2).