" Sharks and dogfishes differ from skates and rays by "

Shark is

Shark is

Sharkes are

Sharkes are

Sharkes are

Sharks lack

Sharks and bony fish are different in that only :

What are cathode rays and how do they differ from positive rays ?

How do cathode rays differ from anode rays?

(a) State three properties which are common to both the beta rays and cathode rays. (b) How do beta rays differ from cathode rays ?