How many moles of H2 required to produce 0.50 moles of NH3​

There are main groups in the modern periodic table of elements

How many moles of potassium hydroxide are needed to completely react with 2.94 moles of aluminum sulfate

Which aqueous solution of ki freezes at the lowest temperature? 1) 1 mol of ki in 500. g of water 2) 2 mol of ki in 500. g of water 3) 1 mol of ki in 1000. g of water 4) 2 mol of ki in 1000. g of water