This group of elements is typically non-reactive because they have a full outer shell

group ia (alkali metals)
group viia (halogens)
group viiia (noble gases)
transition metals

Halogens are the only ones that have a full outer shell

organisms are more likely to be more preserved in mud than sand because mud is moist and wet, while sand is very dry.

answers: to make sure that all of the broken pieces of tablet were added to the water, to allow for fair comparison of all three trials, with different particle sizes to avoid experimental error