Step 1: Understanding the properties of spark plug insulators. - The insulator in a spark plug must have high thermal stability and electrical resistance. - Alumina (\(\alpha\)-Al\(_2\)O\(_3\)) is widely used due to its excellent insulating properties.
Step 2: Selecting the correct option. Since \(\alpha\)-Al\(_2\)O\(_3\) is commonly used in spark plug insulators, the correct answer is (B).
LIST I (Material) | LIST II (Form of Microstructure) |
A. Gray Cast Iron | I. Presence of large amount of iron carbide |
B. White Cast Iron | II. Graphite in the form of spheroid |
C. Ductile Cast Iron | III. Graphite exists as rosettes in ferrite or pearlite matrix |
D. Malleable Cast Iron | IV. Graphite in the form of flakes |