The first law of thermodynamics can be written as $\Delta U = \Delta Q + \Delta W$ for an ideal gas. Which of the following statements is correct?

  • A
    $\Delta U$ is always zero when no heat enters or leaves the gas.
  • B
    $\Delta W$ is the work done by the gas in this written law.
  • C
    $\Delta U$ is zero when heat is supplied and the temperature stays constant.
  • D
    $\Delta Q = -\Delta W$ when the temperature increases very slowly.

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