The reason that elements in the same group all have similar chemical properties is because they all have the same
a- number of protons in the nucleus
b- number of neutrons in the nucleus
c- number of electrons outside the nucleus
d- number of electrons in the outer energy level

Dying the folding patterns of protein molecules can microbiologists better understand cellular processes as well as some diseases, such as alzheimer’s, that are caused by proteins that have misfolded. the folding of these complicated molecules can be simulated on computers, but it takes a lot of processor power and time for even expensive supercomputers to do this. a group of researchers at stanford university developed software that can be used to distribute the processing of data to anyone who is willing to donate time on their idle personal computers. as a result, the researchers have been able to achieve protein-folding simulations that are far better than those other computing methods have done. which statement best describes the work of these researchers? the work is not scientific because the data are not processed in one location. the work is not scientific because the simulations are not reproducible. the researchers applied creativity to solve a problem in running an experiment. the researchers used only well-established scientific techniques.

Select the correct answer from each drop-down menu. to make a table of the elements, dmitri mendeleev sorted the elements according to their . he then split the list of elements into several columns so that elements beside each other had similar .

Reacting masses1 calcium carbonate breaks down on heating to produce calcium oxide and carbondioxide gas. caco3 + cao + co2a student heats 15 g of calcium carbonate strongly in a crucible. relative atomic masses (a): ca = 40, c = 12, o = 16.calculate the mass of calcium oxide produced by this reaction.(5 marks)