Give reasons for the following:(i) Ionic compounds have generally high melting points. (ii) Hydrogen is not a metal, but it has been assigned a place in the reactivity series of metals. (iii) The galvanised iron article is protected against rusting even if the zinc layer is broken. (iv) The wires carrying current in homes have a coating of PVC.

Give reasons for the following:(i) Ionic compounds have generally high

1.	Give reasons for the following:(i) Ionic compounds have generally high melting points. (ii) Hydrogen is not a metal, but it has been assigned a place in the reactivity series of metals. (iii) The galvanised iron article is protected against rusting even if the zinc layer is broken. (iv) The wires carrying current in homes have a coating of PVC.
Answer» Solution : (i) There are ELECTROSTATIC forces of ATTRACTION between the cations and anions in ionic compoundswhich are difficult to break. Therefore ionic compounds have high melting points. (ii) Metals above hydrogen evolve hydrogen gas and metals below hydrogen do not evolve hydrogen when treated with an acid. That is when hydrogen has been ASSIGNED a place in the reactivity series of metals. (iii) Even if zinc layer is broken, it will preferentially oxidised because it is more REACTIVE than iron. (iv) The wires CARRYING current in homes have a coating of PVC. This is because PVC is an insulatingsubstance and protects from electric shock.