Desert locusts are devastating
to agriculture because they group in small swarms and can eat the same amount
of vegetation in one day as an elephant. The answer is letter B. a single swarm
contain between 40 and 80 million and can cover up to 1200 square kilometers.
The Mercalli scale measures the intensity of an earthquake. It measures the effects of an earthquake, and is distinct from the moment magnitude usually reported for an earthquake.
Answer:
After three half-lives, it is 7:1
Explanation:
- The rate at which the decay of the radioactive isotope is said to be half-life and is represented as the half-life of the atoms and the matter to disintegrate itself.
- The two radioactive isotopes are K 40 and Ar 40. After the K-Ar dating, they contain minerals such as the clay mica and the temphra minerals and Half-life of the K 40 is 1.3 more than 100,000 years i.e 10x9 years for Ar 40.
- <u>Thus the K 40 has to divide as three half-lives have passed if the ratio of argon to potassium atoms is 7:1. At the end of one half-life, the ratio of the number of argon to potassium atoms is 1:1. and two half lives its 3:1 thus after the third half-life it becomes as 7:1.</u>
