Alright, so mass is a property of a physical body. During physical changes, such as acceleration, force, etc, the mass stays the same since we are not affecting its physical shape, just where it is physics wise. So yeah mass is conserved during a physical change.
(This is very confusing I'm bad at explaining things sorry)
Shells are considered biotic because they come from living things. Biotic describes something living or use to be living such as plants and animals. So shells are considered biotic because they come from a living organism.
~~~~~~~~~~~~~~~~~~~
Hope that helped:)
~~~~~~~~~~~~~~~~~~~
Geiger-Muller tube is instruments requires you test three times the background of the work area.
<u>Explanation</u>:
These detectors are gas filled detectors and hence requires time for responding to the value. This time is taken because during this period it collects the electric charges and features of the electric circuit. It also gets stabilized during this period. This device has thumb rule i.e one must wait or hold for at the least 3 times the time constant before getting the precise and accurate reading. The time constant order is 10 seconds for the ionization chamber but for the Geiger counter it can vary from seconds to greater than 20 seconds
It’s length and sequence of nitrogen bases