Answer
See explanation
Work Step by Step
a. CU and Cu
Cu → Copper, a metallic element (atomic number 29).
CU → Not a valid element symbol (element symbols have only the first letter capitalized).
Answer:
Only Cu is an element — copper.
b. Os and OS
Os → Osmium, a transition metal (atomic number 76).
OS → Not a valid element symbol (could be interpreted as “O” + “S” = oxygen and sulfur, but not a single element).
Answer:
Only Os is an element — osmium.
c. Ni and NI
Ni → Nickel, a transition metal (atomic number 28).
NI → Not a valid element symbol (capitalization is incorrect).
Answer:
Only Ni is an element — nickel.
d. BIN, BiN, and BIn
BIN → Not a valid element (improper capitalization).
BiN → Combination of bismuth (Bi) and nitrogen (N) — a compound formula, not a single element.
BIn → Combination of boron (B) and indium (In) — also a compound, not a single element.
Answer:
None of these are single elements.
