Concept:The mechanical work done during the expansion or compression of a gas is calculated using pressure-volume formulas. Depending on the convention (physics vs. chemistry), the absolute magnitude is identical.
Formula:$$ W = P \times \Delta V $$
Solution:- The constant external pressure (\( P \)) = 2 atmospheres.
- The change in volume (\( \Delta V \)) = \( V_{\text{final}} - V_{\text{initial}} = 20 - 15 = 5 \text{ dm}^3 \).
- Work magnitude = \( 2 \text{ atm} \times 5 \text{ dm}^3 = 10 \text{ atm.dm}^3 \).
- Note: In standard IUPAC chemistry convention, expansion work is done by the system and is technically negative (\( -10 \text{ atm.dm}^3 \)). However, the ETEA key and provided options utilize the absolute magnitude / physics convention yielding a positive \( 10 \text{ atm.dm}^3 \).
Why other options are incorrect:Values of 5 or -5 arise if the pressure is completely ignored or misapplied.
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