Answer:
Boiling water is an example of a physical change and not a chemical change because the water vapor still has the same molecular structure as liquid water (H2O).
Explanation:
B. It is open to change as new evidence or data is discovered. If scientists discover new evidence, they must modify their theories to conform with the new data.
A. is <em>incorrect</em>. Scientific laws are so well established that there can be no exceptions.
C. is <em>incorrect</em>. A scientific theory is the collective judgement of scientists as to the best explanation for a phenomenon. A new observation may require modification of the theory.
D. is <em>incorrect</em>. Advancements in technology can provide new evidence that requires new explanations.
<span>B. 51 50
Z and Z
25 25
It is because only this element have equal number of Protons (Bottom number) and are different in atomic masses (upper number)
Hope this helps!</span>
Answer: Chemical composition modification (or, physical signal would be color).
The low-mass elements, hydrogen and helium, were produced in the hot, dense conditions of the birth of the universe itself. The birth, life, and death of a star is described in terms of nuclear reactions. The chemical elements that make up the matter we observe throughout the universe were created in these reactions.
