Answer:
14 cm squared
Step-by-step explanation:
The shaded triangle is clearly half of the rectangle, and half of 28 is 14.
The other way you can look at it is that the dimensions of the rectangle are 4 cm and 7 cm. The area of a triangle equation is . So
is 14.
Answer:
A) 277 million years
Step-by-step explanation:
Here, decay of U-238 is first order reaction. (since most of the nuclear decays are first order).
so, the equation t = × ln(
)
where, t = time from start of reaction
k = reaction constant
A(0) = initial concentration; A = present concentration.
⇒ 4.5 billion = 4500 million years = × ln2.
Now, given 95.82% of parent U-238 isotope is left.
⇒ t = × ln(
)
t = × ln(
)
⇒ t ≅ 277 million years.
