Question

exam lesson name: chemistry
exam number: 700700rr
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question 10 of 20 :
select the best answer for the question.

1. which of the following chemical equations is balanced?

a. koh + h₂so₄ → khso₄ + h₂o
b. 2na + s → 2nas
c. 2nacl + h₂so₄ → hcl + naso₄
d. nh₃ + h₂o → 2nh₄oh
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Explanation:

Step1: Analyze Option A

Count atoms on each side. Left: K=1, O=1 (from KOH) + 4 (from \(H_2SO_4\)) = 5? Wait, no: KOH has K=1, O=1, H=1; \(H_2SO_4\) has H=2, S=1, O=4. So left: K=1, O=1+4=5, H=1+2=3, S=1. Right: \(KHSO_4\) has K=1, H=1, S=1, O=4; \(H_2O\) has H=2, O=1. So right: K=1, O=4+1=5, H=1+2=3, S=1. Balanced. Wait, let's check others.

Step2: Analyze Option B

Left: Na=2, S=1. Right: \(NaS\) (should be \(Na_2S\) maybe? Wait formula: 2Na + S → 2NaS. Na on right: 21=2, S on right: 21=2. But left S=1. So unbalanced.

Step3: Analyze Option C

Left: Na=2, Cl=2, H=2, S=1, O=4. Right: HCl (H=1, Cl=1), \(NaSO_4\) (Na=1, S=1, O=4). So right: H=1, Cl=1, Na=1, S=1, O=4. Not balanced (Na, Cl, H).

Step4: Analyze Option D

Left: N=1, H=3+2=5, O=1. Right: \(2NH_4OH\) has N=2, H=2(4+1)=10, O=21=2. Unbalanced.

Answer:

A. \( \text{KOH} + \text{H}_2\text{SO}_4
ightarrow \text{KHSO}_4 + \text{H}_2\text{O} \)