$10.$ In diaphragm cells, what is the diaphragm made of$?$

$-$ a$)$ Asbestos

$-$ b$)$ Polypropylene

$-$ c$)$ Nafion

$-$ d$)$ Glass

$11.$ Which of the following is a major advantage of membrane cells over diaphragm cells?

$-$ a$)$ Lower operational cost

$-$ b$)$ Higher purity of products

$-$ c$)$ Simpler construction

$-$ d$)$ Lower energy consumption