All substances are composed of elements such as water (H2O) is composed of hydrogen (H) and oxygen (O), carbon dioxide (CO2) is composed of carbon (C) and oxygen (O), nitrogen (N2) is. contain nitrogen (N)
All kinds of substances is composed of elements such as water (H2O) is composed of the element hydrogen (H) and oxygen (O), carbon dioxide (CO2). Consists of carbon (C) and oxygen (O), nitrogen (N2) consists of nitrogen (N) .