Answer: hello the complete question is attached below
Visibility of molecular ion = m/z value of 77
Explanation:
For The molecular ion to be visible, it has to be at an m/z value of 77 and this is because molecular ions will have an m/z ratio = molecular mass of given molecule in most cases but not always in all cases.
And the visibility is possible after the removal of CH₃ ion.
ii) Evidence in the mass spectrum that suggests peak at m/z = 77
attached below
