Explain why atomic radius decreases as you move from left to right across a period

How many liters of oxygen gas, at standard temperature and pressure, will react with 35.8 grams of iron metal? 4 fe (s) + 3 o₂ (g) → 2 fe₂o₃ (s)

Is 343 in the sequence -5, -2, 1, 4, 7

15) a substance used in manufacturing gasoline consists of finely divided platinum supported on an inert solid. suppose that the platinum is formed by the high temperature reaction between platinum (iv) oxide and hydrogen gas. the other product is water. a) write and balance the equation b) how many grams of hydrogen are needed to produce 1.0 g of platinum metal? c) how many moles of water are produced at the same time? how many grams? ( show work, .)