Answer: A
Explanation: The answer is A.
Answer:
A)11,460 years
Explanation:half of a radioactive element represent the time take for half of it's components to dissociate or disintegrate.
For carbonn14 that undergo an emmision to form a stable carbon 14,it moves thus
14C(1 part) ______14C(0.5 parts)_____14C(0.25parts)
i.e it undergo two radioactive decay which means two half lives .
Since each half life is 5780 years ,the age will be 2×half lives= 2×5780=11,460 years
Gradual changes in the frequency of diseases over long periods are known as SECULAR TIME TRENDS. For example, the rate of mortality in USA due to coronary heart diseases over a period of time. Onset of puberty in girls is also a secular time trend.
Secular time trend is also referred as Secular Variation and Secular Drift.
The two biggest reasons for children spending less time outside are the development of technology and the safety issues. The development of technology brought in our homes countless forms of having fun which is very important to children. The mobile phones, PC's, laptop's, tablets, Sony Play Station, as well as lots of technologically improved toys, made the children stay at home since they have the fun indoors, and not be interested in going outside and in nature. Also the safety issues in lots of parts in the world made the parents to restrict the children to the indoors environment.
