<h2>12km</h2>
<em><u>Explanation:</u></em>
1 cm = 4 km
3 cm = 4×3 km
= 12 km
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The study of the weather in these early years is important because it can help students understand that some events in nature have a repeating pattern. It also is important for students to study the earth repeatedly because they take years to acquire the knowledge that they need to complete the picture.
Weather fronts do the same thing - they advance forward, creating weather changes and sometimes even violent storms along the front. ... Thunderstorms are common along cold fronts. This is because when a cold front occurs from a cold air mass moving into a warm air mass, the warm air is forced upward.
Because water is water. humans need water to survive, so if the water in the bottle is considered to be clean ( without any added chemicals) it is then against our rights.
Earth is the 3rd closest.
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
learn more
Radioactive decay brainly.com/question/10125168
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