Answer:
The rock is 3.75 billion years ago.
Explanation:
Given that:
Half life = 1.25 billion years
1 billion years = 10⁹ years
So,
Half life = 1.25 × 10⁹ years

Where, k is rate constant
So,


The rate constant, k = 5.5452 × 10⁻¹⁰ years⁻¹
Initial amount [A₀] = 80 micrograms
Final amount
= 10 micrograms
Using integrated rate law for first order kinetics as:
![[A_t]=[A_0]e^{-kt}](https://tex.z-dn.net/?f=%5BA_t%5D%3D%5BA_0%5De%5E%7B-kt%7D)
So,





So,
<u>The rock is 3.75 billion years ago.</u>
<u>Answer:</u>
King Sennacherib ruled the area of Assyria from 705 B.C. to 681 B.C. He was basically known for building beautiful places and loved to develop places and to extend them.
He also developed walls in the inner and outer parts of the city which would stand straight and strong for years together. He mostly built these projects in the city of Nineveh. He also designed the system of water distribution and planned new streets.