Tooth enamel is made up of which one of the following calcium compounds?

Which of the following metals cannot be easily cut by a knife?

A. aluminium

B. sodium

C. potassium

D. lithium

. . . . . . . . is the most ductile metal.

A. Cu

B. Al

C. Au

D. Zn

The chemical structure of the pearl is

A. Calcium Carbonate

B. Calcium Carbonate & Magnesium Carbonate

C. Calcium Chloride

D. Calcium Sulphate

Stainless steel does not rust because

A. chromium and nickel combine with iron

B. chromium forms an oxide layer and protects iron from rusting

C. nickel present in it, does not rust

D. iron forms a hard chemical compound with chromium present in it