Question

select one:
a. i and ii
b. ii and iii
c. ii and iv
d. iii and iv

which of the following is a diatomic molecule?
select one:
a. naf
b. o₂
c. ki
d. nh₃

Explanation:

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First Question (Atomic Structure)

Step1: Calculate atomic number (protons)

For each diagram:

• I: $Z=2$ (2 protons)
• II: $Z=4$ (4 protons)
• III: $Z=10$ (10 protons)
• IV: $Z=8$ (8 protons)

Step2: Count total electrons

• I: $2 + 2 = 4$ electrons
• II: $2 + 4 = 6$ electrons
• III: $2 + 8 = 10$ electrons
• IV: $2 + 6 = 8$ electrons

Step3: Identify neutral atoms

Neutral atoms have equal protons/electrons:

• III: $10=10$ (neutral)
• IV: $8=8$ (neutral)

A diatomic molecule consists of exactly two atoms. NaF and KI are ionic compounds (not molecules), $\text{NH}_3$ has 4 atoms, while $\text{O}_2$ contains two oxygen atoms.

Answer:

d. III and IV

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Second Question (Diatomic Molecule)