The model is based on hypothesis to get an initial idea for analyzing a complex problem. Hence, the validity of a model is limited and may not be valid universally. On the other hand, theories and laws are confirmed hypothesis which are universally valid. These are formulated after repeated testings. theories are more explanatory.
Answer:
1st, 2nd, and 4th
Explanation:
1st conserves gasoline/petroleum
2nd conserves electricity
4th conserves paper
What is the question? I think that you answered it yourself...
The 26th is Fe(iron) and the 50th is Sn(tin)