21.The metal rim is made slightly______than the wooden wheel.
Bigger
Smaller
Either smaller or of same size
None of these
Dear Student,
The iron rim is smaller than the wooden wheel. The iron rim is heated so that it expand. When its size becomes larger than wooden wheel it is slipped on the wheel. After that cold water is poured on the wheel so that on cooling the rim contracts and holds the wooden wheel tightly.
Hence (b) is the correct option.
Regards