Which of the following is the strongest bond?

What are electron-deficient compounds? Are $BCl_3$ and $SiCl_4$ electron-deficient species? Explain.

The electronic configuration of $X$ and $Y$ are given below:
$X: 1s^2 2s^2 2p^6 3s^2 3p^3$
$Y: 1s^2 2s^2 2p^6 3s^2 3p^5$
Which of the following is the correct molecular formula and type of bond formed between $X$ and $Y$?

Which of the following molecules is electron-deficient?

The two types of bonds present in $B_2H_6$ are covalent and

Which of the following is true for the pair of electrons in a bond between two identical non-metal atoms?