3. How many moles of oxygen are required to react completely with 5.00 grams of hydrogen? 4. Iron (III) oxide, Fe 2 O 3 formed when iron, Fe, combines with oxygen in the air. How many grams of Fe 2 O 3 formed when 12.5 g of Fe reacts completely with oxygen?

Which element in the third period would you expect to have the larger atomic radius, sodium (na) or sulfur (s)? a. sodium, because it has a higher effective nuclear charge attracting electrons in fewer energy levels. b. sodium, because it has fewer protons attracting electrons in the same energy levels. c. sulfur, because it has more protons attracting electrons in more energy levels. d. sulfur, because it has a higher effective nuclear charge attracting electrons in the same energy levels.

Determine the empirical formula for succinic acid that is composed of 40.60% carbon, 5.18% hydrogen, and 54.22% oxygen.

Nebulae are enormous clouds in outer space. they are made mostly of hydrogen gas, helium gas, and dust. some nebulae glow brightly, while others do not. the stars that people see are huge, bright balls of glowing gas. they are made mostly of hydrogen and helium. which statement correctly describes other ways in which nebulae and stars are different? a. stars can form inside a nebula but a nebula can never be produced by any star. b. a star always has a higher density than a nebula. c. stars can never form inside a nebula but a nebula can be produced by any star. d. a nebula always has a higher density than a star.