Answer:
Volcanic rock-lichen-mosses-sea grasses
Explanation:
Lichens are complex living beings that form a symbiosis of an organism formed by a fungus and an algae or cyanobacterium. They're known for interacting with volcanic rocks. Moss is a cosmopolitan phylum of small, simple-organized, and non-vascular cryptogamous plants that typically grow in dense tufts, which are more common in humid and dark habitats. They're the ones to come after the lichens during primary succession of volcanic island environments. Marine angiosperms, also known as, sea grasses, are the flower-producing plants adapted to life in seawater that form marine meadows on the euphotic bottoms of the oceans. They install themselves on the coasts that are populated by mosses, therefore not being uncommon to see in volcanic islands.
Answer:
2.5 mg
Explanation:
<em>The half-life of a substance is the time required for one half of the substance to decay. In order words, it is the time it will take for a substance to decay into half of its initial size.</em>
For a 20 mg element with a half-life of 30 which decays over a period of 90 years;
The first 30 years, 10 mg would have decayed, remaining 10 mg
The second 30 years, the remaining 10 mg would have decayed to 5 mg
The third 30 years, 5mg would have decayed to 2.5 mg.
Hence, in 90 years, 20 mg of the element would <u>remain only 2.5 mg.</u>
