Which of the following statement(s) are correct for nitrogen family elements?

Oxidation state from +1 to +4 for nitrogen tend to disproportionate in acidic medium.

Phosphorous and arsenic can form  $d\pi -d\pi$ bond with transition metals.

The only basic oxide of N-family is  $B{i}_2{O}_5$.

The only trihalide  $Bi{F}_3$ is ionic in nature.