After two half-lives or 60 years, 7.5 g of the element will be left.
<u>Explanation:</u>
<u>Half-life:</u>
- In simple words, Half-life can be defined as the amount of time needed for a quantity to fall to half its value as contained at the beginning of the time period.
- In this problem the half-life of the element is thirty years, then after thirty years half of the sample would have decayed and half would be left as it is.
- After thirty years (The first half-life ) 30 /2 = 15 g declines and 15 g remains disappeared.
- And after another sixty years (The two half-lives) 15 /2 = 7.5 g declines and 7.5 g remains disappeared.
- After two half-lives or 60 years, 7.5 g of the element will be left.
The population of Green-feathered birds decreases due to prefer other colour of male birds.
<h3>Why the population of Green-feathered birds decreases?</h3>
Green-feathered birds are becoming less and less common because of the female bird that choses the blue and red colour male for mating instead of green so that's why the population of Green-feathered birds decreases.
Learn more about mechanism here: brainly.com/question/1320373
Answer:
The left side of the brain is responsible for controlling the right side of the body. It also performs tasks that have to do with logic, such as in science and mathematics.
Explanation:
Basically controls the opposite side of your brain and used for brain intensive tasks.
To prevent cancer, over exposure to radiation
