I think this is the answer you was looking for hope this helps !!!
Potassium would not have similar properties because it is the alkali metals, not alkali earth metals
Your answer is B and the element is Carbon
So what your looking for is matching isotopes. Isotopes are elements that are the same in amount of protons but different in mass meaning different number in neutrons. Because when you add the total protons and neutrons together you get your atomic mass. So this can be written as X=said element, top number above=different atomic mass, bottom number below=atomic number. Hope this help!!
Be careful because answer A has same masses but different atomic numbers so different atoms(elements)!!!
Equation for oxygen gas molecules
1.5O₂ + 2Al => Al₂O₃
ratio of aluminium to oxygen is
2:1.5
when Al is 7.5
O₂ is 3.75
Non polarcompound I think so