# If 50 calorie are added to a system and system does work of 30 calorie on surroundings, the change in internal energy of system is: Option 1) 20 cal. Option 2) 50 cal. Option 3) 40 cal. Option 4) 30 cal.

As learnt in

IUPAC Sign Convention -

Any type of energy (Heat, Work ) given to system is positive

Any type of energy take out from the system

- wherein

$W= +10 j$ i.e. 10 J work done on the system

$q= -10 j$ i.e. 10 J released by the system

First law of Thermodynamics -

Energy of universe is always conserved or total energy of an isolated system is always conserved

$\Delta E= q + W$

- wherein

$\Delta E=$ Internal Energy

$q=$ Heat

$W=$ work

$\Delta E= g -w$ (work is done by the system, so w= -ve)

= 50 -30

= 20 cal

Option 1)

20 cal.

correct

Option 2)

50 cal.

Incorrect

Option 3)

40 cal.

Incorrect

Option 4)

30 cal.

Incorrect

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