Which type of bond is formed between similar atoms?

Write the limitations of the Lewis covalent bond theory.

Identify the molecule containing a triple bond.

In which one of the following molecules is the strongest back donation of an electron pair from halide to boron expected?

The number of electrons involved in the bond formation of $N_2$ molecule is:

Among $B_2H_6, B_3N_3H_6, N_2O, N_2O_4, H_2S_2O_3$ and $H_2S_2O_8$,the total number of molecules containing a covalent bond between two atoms of the same kind is . . . .