Answer:
element
Explanation:
we know that helium is a pure substance although helium atoms are sometimes mixed with their isotopes it is still the same element. since there is no other element combined with helium this makes it an element.
Answer: acid
Explanation: it dissolves in water to produce hydronium ion as the only positive ion
It emits hydrogen sulfide...smells like rotten eggs..
ty:)pls let me know whether this is ryt:D
compound is sp3.
B.