Answer:
Look at my answer to the last one, and see if you can solve this one on your own!
After you try it, I can let you know if you got it right :)
5. is b
but im not sure about 4
hope this helps
A physical property of an element is a property of an element that can observed or measured without changing the chemical nature of the element.
A chemical property of an element is a property of an element that can only be observed or measure when the chemical property of the element is altered or changed.
Based on this;
The boiling point of bromine is a physical property of bromine.
The high reactivity of bromine with many elements is a chemical property of bromine.
Cs -137 has a half life of about 30 years. If 60 years pass, there is two half lives passed so 1/2 * 1/2= 1/4. Take 1/4 and multiply it with the mass given:
(1/4)*20mg=5mg left
