HELP ASAP What did Dmitri Mendeleev contribute to science?
A. He discovered many unknown elements.
O B. He arranged the first periodic table.
O C. He developed the first atomic theory.
D. He developed the first model of the atom.

Use the drop-down menus to answer each question. which runner finished the 100 m race in the least amount of time? which runner stopped running for a few seconds during the race? at what distance did anastasia overtake chloe in the race?

Consider the following reactions. (note: (s) = solid, (l) = liquid, and (g) = gas.) mg(s) + ½o2(g) → mgo(s) + 146 kcal/mole h2(g) + ½o2(g) → h2o(g), δh = -57.82 kcal/mole what type of reaction is represented by the previous two examples?

Which of the following are correct values for the ideal gas laws constant r