To a sample of an element. X (atomic mass 70) another element Y, (atomic mass 120) is added as an impurity. The ratio of the atoms of the two elements in the mixture is found to be 1 `xx` 10-7. The weight in grams of Y added with 100 g of X would be
1 `xx` 10-7g
1 `xx` 10-6 g
1.714 `xx` 10-5g
1.714 `xx` 10-4 g