The correct order of bond angle is:
If the unpaired electron is present in the central atom then formed bonds will feel repulsion by that unpaired electron. Hence the angle between the bond and the unpaired electron will increase as well as the bond angle between the two bonds will decrease.
has no unshared electron and hence it is linear.
has one unshared electron while
has one unshared electron pair.
Hence, option number (4) is correct.
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