How would you identify substances in a question

Which substances have / _/Hf = 0 kJ/mol by definition? Select all that apply. O2 (g) N (g) H2O (l) Br2 (l) Fe (s) He (g) S6 (s)

Given the balanced equation below, calculate the moles of aluminum that are needed to react completely with 17.5 moles of FeO? Show all work 2Al+3FeO->3Fe+Al2O3

The chemical equation of magnesium and nitric acid

Which statement about limiting factors is false? A. Limiting factors are conditions that affect an organism's chance of survival. B. Limiting factors only affect producers. C. Limiting factors differ from ecosystem to ecosystem. D.

A 1.0 M H2S solution has a pH = 3.75 at equilibrium. What is the value of Ka? A. 3.16 * 10-21 B. 3.16 * 10-8 C. 8.89 * 10-5 D. 8.89 * 10-8

How many moles are in 10 grams of CaCl2?

Which is the correct formula for phosphorus pentachloride? PCl4 because a subscript of 4 indicates four Cl atoms PCl5 because a subscript of 5 indicates five Cl atoms P5Cl because a subscript of 5 indicates five P atoms P5Cl3 because a subscript of

Why are the elements in groups 3 to 12 often used to make dyes?

What is not needed for corrosion of metals? a. oxygen c. water b. ions d. sunlight

What force can move the oceans