1st --> number of molecules in 0,65g SF₆:

2nd --> <span>How many grams of NH3 are needed to provide 2,68</span>ˣ10²¹ molecules
The following are true:-
An atom of oxygen and the ion of oxygen both have 8 protons.
As you add or remove neutrons from the nucleus, isotopes are formed.
Check the attached file for the solution.
The shape is in the next file.
The statement that is an alloy is just another word for a chemical compound of fixed composition that is made of two or more metals is false.
An alloy refers to the mixture of the elements in which the parent element is the metal. An alloy is produced by the amalgamation of any element, that is, metal or non-metal to better the feature of the parent metal. The whole components in the alloy are combined to produce a mixture of fixed composition, but not a chemical compound, and it is not essential that the elements involved are metals. Thus, the mentioned statement is false.