$5.$ In the Solvay process, the ammonia recovery involves the reaction of $\_($a$)\_$ with $\_($b$)\_$ to produce $\_($c$)\_.$

$-($a: Ammonium chloride, Calcium carbonate, Sodium bicarbonate$)$

$-($b: Calcium hydroxide, Water, Ammonia$)$

$-($c: Calcium chloride, Calcium carbonate, Ammonium bicarbonate$)$

$6.$ The membrane cell process for producing caustic soda uses $\_($a$)\_$ as the membrane, separates the $\_($b$)\_$ and $\_($c$)\_$ products effectively.

$-($a: Ion$-$selective, Asbestos, Polymer$)$

$-($b: Chlorine, Hydrogen, Sodium$)$

$-($c: Sodium hydroxide, Water, Sodium chloride$)$