Question

1. choose the best answer.

what was a contribution from julius lothar meyer to the development of the periodic table?
he arranged elements in periods using similar physical properties.
all positions in the periodic table were filled with an element.
elements were arranged according to their chemical properties.
elements lithium through titanium were in a row.

1. choose the best answer.

who filled in the gaps or empty positions in meyers periodic table?
stanislao cannizzaro
john dalton
albert einstein
dmitri mendeleev

Explanation:

For question 1: Julius Lothar Meyer focused on physical properties. He arranged elements in periods using similar physical properties. The other options are incorrect. Not all positions were filled (Mendeleev left gaps). Arranging by chemical properties was more Mendeleev's emphasis. The statement about lithium - titanium is not his main contribution.
For question 2: Dmitri Mendeleev filled the gaps in the periodic table. Stanislao Cannizzaro's work was on atomic weights. John Dalton proposed atomic theory. Albert Einstein's work was in physics (not related to filling periodic table gaps).

Answer:

1. He arranged elements in periods using similar physical properties.
2. Dmitri Mendeleev