21.
Statements : Some pots are keys. Some keys are locks. All keys are rings.

Conclusions :
I. Some pots are locks.
II. Some pots are not locks.
III. Some pots are rings.
IV. Some pots are not rings.

22.
Statements : Some actors are singers. All the singers are dancers.

Conclusions :
I. Some actors are dancers.
II. No singer is actor.

23.
Statements : All the harmoniums are instruments. All the instruments are flutes.

Conclusions :
I. All the flutes are instruments.
II. All the harmoniums are flutes.

24.
Statements : Some mangoes are yellow. Some tixo are mangoes.

Conclusions :
I. Some mangoes are green.
II. Tixo is a yellow.

25.
Statements : Some ants are parrots. All the parrots are apples.

Conclusions :
I. All the apples are parrots.
II. Some ants are apples.