If three half lives have passed since a scientist collected 100 grams of sodium 24 , how much Na-24 is left now? 0 grams
24 grams
50 grams
12.5 grams
100 grams

his research revealed two genetically different groups of prokaryotes, which justified splitting kingdom monera into two kingdoms. the genetic and cellular differences were so great, that these two kingdoms were eventually placed into different domains in the current three-domain system.

one characteristic that is shared by all is a soft body. many

of these invertebrate animals also have an outer shell to protect their

body. oysters, clams, snails, and mussels are all mollusks. so are octopuses, squids, and slugs. mollusks live on land and in freshwater.

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is this a question? wassup