Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties. + 18 others found this useful. Jack Bakhet. Edit. Share to: Chrishan Silva. 509,209 Contributions. I'm an undergraduate in Physical Sciences stream.
1 Two gases make up the bulk of the earth's atmosphere: nitrogen (), which comprises 78% of the atmosphere, and oxygen (), which accounts for 21%. 2  Various trace gases make up the remainder. 3  Based on temperature, the atmosphere is divided into four layers: the troposphere, stratosphere, mesosphere, and thermosphere.
Air is made almost entirely of two gases. The most common gas is nitrogen, and the second most common gas is oxygen (O2). Nitrogen and oxygen together make up 99% of the planet's atmosphere. All other gases together make up the remaining 1%.