The correct option is A I II III IV
+ − − +
△ng= moles of gaseous products - moles of gaseous reactants
If △ng=+ve - expansion
If △ng=−ve - contraction.
work of Expansion is -ve
Work of contration is +ve
For reaction 1,
△ng=2−(3+1)=−2=−ve - contraction, which means +ve work.
For reaction 2,
△ng=1+1−(0)=2=+ve - expansion, which means -ve work.
For reaction 3,
△ng=2−(1)=1=+ve - expansion, which means -ve work.
For reaction 4,
△ng=2−(4.5)=−2.5=−ve - contraction, which means +ve work.
So, The work done in the reaction 1, 2, 3 and 4 is + , - , - , + respectively.