Name the following compound: ZnCO3 a) Zinc (II) carbonate b) Zinc (I) carbonate c) Zinc carbonate d) Zinc carbide QUESTION 14 The correct name for SrO is: a) strontium(II) oxide b) strontium hydroxide c) strontium oxide d) strontium monoxide QUESTION 15 Of the choices below, which one is a molecular compound? a) FeCl2 b) KBr c) RbCl d) OF2
The Correct Answer and Explanation is:
QUESTION 13
Name the following compound: ZnCO₃
Correct answer: a) Zinc (II) carbonate
QUESTION 14
The correct name for SrO is:
Correct answer: c) strontium oxide
QUESTION 15
Which one is a molecular compound?
Correct answer: d) OF₂
Explanation
Question 13 – ZnCO₃: Zinc (II) carbonate
Zinc carbonate is composed of the zinc ion (Zn²⁺) and the carbonate ion (CO₃²⁻). Since zinc commonly forms only a +2 charge, the Roman numeral II is appropriate, even though it’s often omitted for elements with fixed oxidation states like Zn. So, the correct IUPAC name is zinc (II) carbonate. Option a is correct. Options b and c are incorrect because Zn⁺ (zinc I) does not exist in stable compounds. Option d, zinc carbide, is unrelated.
Question 14 – SrO: strontium oxide
Strontium (Sr) is an alkaline earth metal that always forms a +2 charge (Sr²⁺). Oxygen typically has a −2 charge (O²⁻). Combining them in a 1:1 ratio yields SrO. Because Sr has a fixed oxidation state, there’s no need to specify it with Roman numerals. Thus, strontium oxide is the correct name, making option c the right answer. Option a is incorrect because the Roman numeral is unnecessary. Option b refers to a different compound entirely (Sr(OH)₂), and option d is not a conventional or correct name.
Question 15 – Molecular compound: OF₂
Molecular compounds are typically formed between two nonmetals. OF₂ (oxygen difluoride) consists of two nonmetals: oxygen and fluorine. These elements form covalent bonds, making it a molecular compound. In contrast:
- FeCl₂ is an ionic compound (metal + nonmetal),
- KBr is ionic (metal + nonmetal),
- RbCl is also ionic (metal + nonmetal).
Therefore, the only molecular compound among the options is OF₂, making d the correct choice.
