Sr will always have 38 protons because that is its atomic number. Normally Sr has 38 protons and 49 neutrons yielding an atomic mass of 87. unless you are dealing with an isotope of Strontium in which 3 additional neutrons would give you the 53 neutrons in your answer, (38p, 52n).
B . microscope
this is the answer .
The amount of kinetic energy that an object has depends on its mass or how heavy it is and how fast it is moving, or velocity
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