Electric Cable used in fire alarm systems has copper wire surrounded by Mg0 (which acts as an insulator) and the whole cable is encased in thin copper tubing.
a) Describe the bonding in MgO an explain why it acts an insulator.
b)Explain why MgO is preferred to pvc as an insulator.
c)Suggest a reason why copper is suitable for encasing the magnesium oxide.
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Answer: a)Ionic bonding is present in MgO. There are strong electrostatic forces of attraction between Mg2+ and O2- ions lattice. In the solid state, there are no mobile ions to carry a current, and thus MgO acts as an insulator.
b) MgO is preferre because it has a higher melting point. Moreover at high temp, pvc will not only melt, but give off toxie fumes of HCl.
c) It is malleable and resistant to corrosion. It also has high tensile strength and so acts as a support for the powdery MgO
