El hielo es una mezcla, elemento o compuesto?

Write the chemical formula for a compound that is made of an element from group 1 and an element from group 17

Draw two cyclic constitutional isomers of cis-1

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