The correct statement among $\left(1\right)$ to $\left(4\right)$ are 

1. Saline hydride produces $H_2$ gas when reacted with $H_{2}O$

2. Reaction of $LiAl{H}_4$ with $B{F}_3$ leads  to form $B_2{H}_6$

3. $P{H}_3$ and $C{H}_4$ are electron-rich and electron precise hydride respectively

4. $HF$ and $C{H}_4$ are called as molecular hydrides