Question

Why coils of electric toaster and electric irons are made up of alloy rather of pure metal

Answer 1

coils of electric toaster and electric toaster and electric irons are made up of alloy rather of pure metal because the resistance of alloy is higher than than pure metal and alloy do not melt easily at high temprature.

Answer 2

Alloys used in elements of toaster are specially designed to heat up faster, work efficiently, have a high resistance and a high melting point. Pure metals do not have all these properties. Alloys retain the properties of their parent elements. So they have many favourable and required properties. But pure metals few or many of the required properties, not all. They have some or the other negative point where they lag behind.
But keep in mind the favourable and required properties depend on their usage and application. Aircrafts and military machines require materials that are strong, tough and lightweight. Automobiles require materials that are malleable, lightweight, and corrosion-resistant. Medical instruments require metals that are hygienic.