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UAT-UK SPEC: C17MODULE: CHEMISTRYTOPIC ID: ARCH-C-02

Diatomic Mass Spectrometry (m/z Peak Ratios 9:6:1 & 1:2:1) & Molecular Ion Combinations

Master Diatomic Mass Spectrometry (m/z Peak Ratios 9:6:1 & 1:2:1) & Molecular Ion Combinations on the ESAT Chemistry paper. Traditional classroom derivations waste valuable seconds. Using the 2-step Sub-90 invariant elimination method compresses solve time to 35s, saving +105s per question.

Standard Classroom Time
140s
Textbook multi-line derivations bleed exam clock
Sub-90 Target Pace
35s
Comfortably below the 88.8s per-question limit
Time Saved for Review
+105s
Banks clock buffer across 27 questions

2-Step Sub-90 Shortcut Formula

How to eliminate intermediate algebra and solve under 45 seconds.

Launch Interactive Lesson
STEP 1 • SETUP INVARIANT (LINE 1)10–15s
Line 1 (Binomial Ratio): (1:1)2  ⟹  1:2:1(1:1)^2 \implies 1 : 2 : 1 peak heights at m/z=158,160,162m/z = 158, 160, 162.

Establish the structural invariant and eliminate impossible options immediately.

STEP 2 • FAST SOLVE (LINE 2)15–25s
Line 2 (Middle Share): 21+2+1×100%=50%\frac{2}{1 + 2 + 1} \times 100\% = 50\% (25s).

Evaluate the simplified expression using integer factoring or unit elimination.

Distractor Trap Forensics

The predictable cognitive traps engineered by examiners into the wrong options.

TRAP #1factor_of_two_or_stoichiometry_trap

Giving diatomic peak heights as p² : p*q : q² (1:1:1 for Br2 or 9:3:1 for Cl2) without the binomial factor of 2 on the middle peak 2pq

Forgetting that heteronuclear diatomic ions (⁷⁹ᴮr⁸¹ᴮr)+ and (⁸¹ᴮr⁷⁹ᴮr)+ can form in 2 ordered ways (2pq).

Sub-90 Fix: Test invariants before expanding equations.
TRAP #2fence_post_or_domain_trap

Counting m/z peak positions without checking overlapping mass sums across multi-isotope combinations

Treating distinct isotopic pairings with identical total mass as separate m/z peaks.

Sub-90 Fix: Test invariants before expanding equations.
TRAP #3intermediate_stop_trap

Reporting atomic ion peaks (m/z = 35, 37) instead of molecular ion peaks (m/z = 70, 72, 74)

Confusing fragmentation monomer peaks with the parent diatomic molecular ion M+.

Sub-90 Fix: Test invariants before expanding equations.

Try 1 Timed Question: Diatomic Mass Spectrometry (m/z Peak Ratios 9:6:1 & 1:2:1) & Molecular Ion Combinations

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Full Lesson All 15 Questions (ARCH-C-02)
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ARCH-C-02: Diatomic Mass Spectrometry (m/z Peak Ratios 9:6:1 & 1:2:1) & Molecular Ion Combinations (Sample)Chemistry
00:00.0
SUB-90 ZONE (<50S)
0.0s50s Sub-9090s ESAT Budget150s Classroom
Question 1 of 1ARCH-C-02 (6-Card Lesson)Format: Standard 5-Option
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Question 1 of 1 • 90s Target

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