ACT Science Practice Question #1816 (Hard (580)) | Test Citadel
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ACT Science Difficulty: Hard (580)

Digital ACT Science Practice Question #1816

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During beta-minus decay, an Iodine-131 nucleus (Z=53) emits an electron (beta particle) and an antineutrino, transforming into: Experiment Context (Radioactive Decay of Iodine-131): A radiochemist tracked the decay of a pure 80.0 mg sample of Iodine-131 (half-life = 8.0 days), measuring residual mass with a scintillation detector: Table 21: - Day 0: Residual I-131 = 80.0 mg (100% remaining) - Day 8: Residual I-131 = 40.0 mg (50% remaining) - Day 16: Residual I-131 = 20.0 mg (25% remaining) - Day 24: Residual I-131 = 10.0 mg (12.5% remaining) - Day 32: Residual I-131 = 5.0 mg (6.25% remaining)
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Beta-minus decay increases atomic number Z by 1 (I-53 -> Xe-54).

Masterclass Solution & Distractor Trap Analysis

Beta-minus decay: neutron -> proton + electron + antineutrino. Mass number stays 131, atomic number increases by 1 to 54 (Xenon)....

Distractor Analysis: Trap choice eliminates careless test-takers who confuse roots with coordinates...

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