Need chemistry with The number of d-electrons in Fe2+ (Z = 26)

1. The number of d-electrons in Fe2+ (Z = 26) is not equal to that of2.The molecules of which gas have highest speed?3The oldest rocksin the earth's crust were once molten, and came from deep inside theearth. The molten rock, called magma, spewed out in volcanic eruptionsduring the earth;s early life and solidified into hard rock's called4 The law which states that the amount of gas dissolved in a liquid is proportional to its partial pressure is5 The main buffer system of the human blood is