本次代写是一个化学资源相关的Homework
Problem 1. Enrichment factor in Earth’s crust
This table was discussed in Lecture 1 (Ref. Revuelta Ch.1).
Estimate Enrichment Factor for the following critical elements – 5 points each [total 30 points]
- PGMs (Platinum Group Metals) as a group or as Pt+Pd
- Iridium,
- Cesium
- Tellurium
- REEs as a group
- Lithium
Notes:
Please be careful with info on internet. Try to use reliable sources
If you make assumptions, please record them.
Problem 2 – 10 points
He (Helium) is on the critical element list
- Why?
- What are the major applications for He?
- What is the abundance or concentration of He on earth?
- What is its primary resource for extraction?
NOTE: you can use USGS or any other information resource


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