Which two or more substances combine but keeps it properties

For ai it's atomic number is 13 and it's mass number is 27 how many neutrons does it have

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

C=59(f−32)the equation above shows how temperature f, measured in degrees fahrenheit, relates to a temperature c, measured in degrees celsius. based on the equation, which of the following must be true? a temperature increase of 1 degree fahrenheit is equivalent to a temperature increase of 59 degree celsius.a temperature increase of 1 degree celsius is equivalent to a temperature increase of 1.8 degrees fahrenheit.a temperature increase of 59 degree fahrenheit is equivalent to a temperature increase of 1 degree celsius.a) i onlyb) ii onlyc) iii onlyd) i and ii only