Can somebody help me with this??!

For which one of the following reactions is the value of δh° rxn equal to δh° f for the product? a. 2 h2 (g) + o2 (g) → 2 h2o (l) b. n2 (g) + o2 (g) → 2 no (g) c. 2 h2 (g) + o2 (g) → 2 h2o (g) d. h2o (l) + 1/2 o2 (g) → h2o2 (l) e. none of the above

Water is important for the of cells. a: size, shape, and temperature b: temperature, color, and odor c: color, odor, and size d: shape, temperature, and color

Express the following number in scientific notation. 0.026890 =