The pH and pOH scales represent concentrations of [H3O+] and [OH−], respectively. What are the hydronium ion concentration and the hydroxide ion concentration of pure water at 25 °C?

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.

Which statement describes both homogeneous mixtures and heterogeneous mixtures?

The reactions of photosynthesis occur in the of plant cell? a.mitochondria. b. lysosomes. c. chloroplasts. d. chlorophyll