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A chemical process in which heat is absorbed.
A change in which q=30 J, w=44 J.
A process in which a system does work on its surroundings with no change in q.
A process in which work is done on a system and an equal amount of heat is withdrawn.

In how many of these cases does the internal energy of the system decrease? (0,1,2,3,4)

Respuesta :

Answer:

Number of cases where internal energy of system decreases = 1

Explanation:

According to first law of thermodynamics-

                                   [tex]\Delta U=q+w[/tex]

where, [tex]\Delta U[/tex], q and w represents change in internal energy, heat exchanged and work done respectively.

  • When heat is absorbed (q > 0), [tex]\Delta U[/tex] will also increase.
  • When q = 30 J and w = 44 J, [tex]\Delta U[/tex] = (30+44) J = 74 J (positive). So, internal energy of system increases.
  • When q = 0 and system does work on its surroundings (w < 0), [tex]\Delta U[/tex] < 0 (negative). So, internal energy of system decreases.
  • When work id done on system (w > 0) and heat is withdrawn (q < 0) by an equal amount (w = -q), [tex]\Delta U=0[/tex]. So, internal energy does not change.

So, number of cases where internal energy of system decreases = 1

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