The correct order of bond length is :N–N < N=N < N≡NN–N < N≡N < N=NN–N > N=N > N≡NN≡N < N–N < N=N

To determine the correct order of bond length, we need to compare the different types of bonds mentioned in the given sequence. Let's break it down step by step:

1. N–N: This represents a single bond between two nitrogen atoms. Single bonds are generally longer than double or triple bonds, so N–N would have a longer bond length.

2. N=N: This represents a double bond between two nitrogen atoms. Double bonds are shorter than single bonds, so N=N would have a shorter bond length than N–N.

3. N≡NN–N: This represents a triple bond followed by a single bond between two nitrogen atoms. Triple bonds are shorter than double bonds, so N≡N would have a shorter bond length than N=N. However, the single bond N–N would be longer than both N≡N and N=N.

4. N≡N: This represents a triple bond between two nitrogen atoms. As mentioned earlier, triple bonds are shorter than double bonds, so N≡N would have a shorter bond length than N=N.

5. N=NN–N: This represents a double bond followed by a single bond between two nitrogen atoms. Similar to the previous case, the double bond N=N would have a shorter bond length than the single bond N–N.

6. N=N: This represents a double bond between two nitrogen atoms. As mentioned earlier, double bonds are shorter than single bonds, so N=N would have a shorter bond length than N–N.

7. N≡NN≡N: This represents a triple bond followed by another triple bond between two nitrogen atoms. Both triple bonds have the same length, so N≡N would have the same bond length as N≡N.

8. N–N: This represents a single bond between two nitrogen atoms. As mentioned earlier, single bonds are generally longer than double or triple bonds, so N–N would have a longer bond length than N≡N.

9. N=N: This represents a double bond between two nitrogen atoms. As mentioned earlier, double bonds are shorter than single bonds, so N=N would have a shorter bond length than N–N.

Based on the above analysis, the correct order of bond length would be:

N≡NN≡N < N–N < N=N < N≡N < N=NN–N > N=N > N≡NN–N < N–N < N=N