Answer:
Smallpox has had a major impact on world history, not least because indigenous populations of regions where smallpox was non-native, such as the Americas and Australia, were rapidly decimated and weakened by smallpox. During the 18th century the disease killed an estimated 400,000 Europeans each year, including five reigning monarchs, and was responsible for a third of all blindness. After successful vaccination campaigns throughout the 19th and 20th centuries, the WHO certified the global eradication of smallpox in December 1979. Smallpox is one of two infectious diseases to have been eradicated.
Explanation:
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Answer:
A) South Korea does not have an officall
Explanation:
The word that most adequately completes the fragment is Small because the rocks of the Grand Canyon do not span a wide span of geologic time.
<h3>What is geological time?</h3>
Geological time is a term to refer to the frame of reference used to represent the events of the history of the Earth and of life in chronological order. It establishes divisions and subdivisions of the rocks according to their relative age.
<h3>What is the Grand Canyon?</h3>
The Grand Canyon is a colorful and rugged gorge carved out by the Colorado River over millions of years in northern Arizona, United States.
The Canyon was created by the Colorado River, whose course undermined the land for millions of years. It is about 446 km long, has mountain ranges between 6 and 29 km wide and reaches depths of more than 1,600 m.
Additionally, nearly 2 billion years of Earth's history has been exposed as the Colorado River and its tributaries cut through layer after layer of sediment at the same time the Colorado Plateau was uplifted.
According to the above, it can be inferred that the Grand Canyon exposes a small portion of the earth's history because it exposes only about 1.7 to 2 billion years and the Earth is about 4.5 billion years old.
Learn more about the Grand Canyon in: brainly.com/question/10770602
Answer:
Although the total energy received by our planet — and hence, Earth’s total temperature — isn’t affected by our axial tilt, the energy received as a function of latitude is very sensitive to it.
Explanation:
More than 75 percent
Explanation:
Let us carefully analyze this problem:
The half life of the rubidium isotope = 50 billion years
The half-life of a radioactive isotope is the time it takes for it to decay to half of its original amount.
Every 50years, we know that a rubidium isotope would split into half.
Initially when the isotope was formed, we would only have the parent atoms there. There wont be any daughter;
ratio of parent to daughter = 100 : 0
When the isotope decays to half; we would have equal number of parent and daughter:
ratio of parent to daughter at half life = 50 : 50
The age of the earth is about 4.6billion years;
this is;
x 100 = 9.2% of the half-life of the rubidium isotope.
At this time, we should know that only 9.2 percent of the daughter would have been formed.
The remaining parent would be 100 - 9.2 = 90.8% would still be left undecayed.
The ratio of parent to daughter = 90.8 : 9.2
This is more than 75% of the parent
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