Name some chemical reactions in which change of state has been happened

Which type of orbits are found in the principal energy level n = 2 a - s b - s, f c - s, d d - s, p e - s, p, d

Which is a chemical property of iron? a. it forms iron oxide (rust) when exposed to moisture and air. b. it is a gray–black metal that is hard to the touch. c. it has a melting point of 2795°f (1536°c). d. it is a good conductor of heat

Consider the four elements above. which one of these elements will combine with oxygen in a 1: 1 ratio?