A liquid when kept inside a thermally insulated closed vessel at $25^{\circ} \mathrm{C}$ was mechanically…

A liquid when kept inside a thermally insulated closed vessel at $25^{\circ} \mathrm{C}$ was mechanically stirred from outside. What will be the correct option for the following thermodynamic parameters ?
  1. $\Delta \mathrm{U} \lt 0, \mathrm{q}=0, \mathrm{w} \gt 0$
  2. $\Delta \mathrm{U}=0, \mathrm{q}=0, \mathrm{w}=0$
  3. $\Delta \mathrm{U} \gt 0, \mathrm{q}=0, \mathrm{w} \gt 0$
  4. $\Delta \mathrm{U}=0, \mathrm{q} \lt 0, \mathrm{w} \gt 0$

Solution

Thermally insulated $\Rightarrow q=0$ from $\mathrm{I}^{\text {st }}$ law
$\begin{aligned}
& \Delta \mathrm{U}=\mathrm{q}+\mathrm{w} \\
& \Delta \mathrm{U}=\mathrm{w} \\
& \mathrm{w}>0, \Delta \mathrm{U}>0
\end{aligned}$

Asked in: JEE Main 2025 (22 Jan Shift 1)

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