Answer: Option (C)
Explanation: Non renewable resources refers to those resources that cannot be regenerated after being used. This are also known as the conventional energy resources. They are formed from the decay of ancient planta and animals that were buried millions of years ago. For example, coal, petroleum, oil and natural gas.
This <u>amount of this resources are present on the earth in a very fixed amount and have great economic significance</u>. Since it is present in a very small amount, so it must be use carefully and if possible should make minimum use of it.
In order to sustain this resources, alternate renewable resources are being used.
Thus, the correct answer is option (C).
Using the principles of cross-cutting relationships, you can determine the relative age of rocks found in the ground. The idea behind it is that the geologic feature which cuts another is the younger of the two features, and it had been around for 400 years. It's not very precise but it is good for determining relative age.
5 percent is the correct answer
Answer:
B and C
Explanation:
B. In a given rock sample, the amount of Silicon-32 isotopes gets divided in half about every 170yrs.
This is the concept of half-life. Half life is the time take for half of a radioactive isotope to disintegrate. The shorter the half life the faster the isotope disintegrates.
From the question, we were told that it would take 170yrs for half of the isotope of Silicon to disintegrate to Phosphorus. This is the half life.
C. The half life can be used to determine the amount of Si-32 that has decayed from the time closure temperature was reached.
The closure temperature is very important in radioactivity. It is the temperature at which a system has cooled and there is no resulting disintegration of parent and daughter isotopes.
From first order kinetics, we know that the rate at which radioactive elements decay at any time is directly proportional to the number of radioactive atoms present. A knowledge of the half life helps to figure out the number of atoms that has decayed in time.
