Understanding Corrosion and Its Prevention

The video tutorial explains corrosion, focusing on rust formation when iron is exposed to moist air. An experiment with three test tubes demonstrates the conditions under which iron rusts. Test tube A, containing air and water, shows rusting, while test tubes B and C, with only water and dry air respectively, do not. The tutorial also covers methods to prevent rusting, such as painting, galvanizing, and alloying, highlighting the benefits of these techniques in protecting iron and steel.

What is the brownish flaky substance that forms on iron when it rusts?

• Rust

• Copper oxide

• Silver tarnish

• Aluminum foil

In the rusting activity, what is the purpose of adding oil to test tube B?

• To react with calcium chloride

• To increase the moisture content

• To prevent air from dissolving in water

• To dissolve the iron nails

Which test tube in the activity shows rusting of iron nails?

• None of the test tubes

• Test tube A

• Test tube B

• Test tube C

What conditions are necessary for iron to rust?

• Both air and water

• Neither air nor water

• Only water

• Only air

Which of the following is NOT a method to prevent rusting?

• Painting

• Oiling

• Exposing to moist air

• Galvanizing

What is galvanization?

• Coating with a thin layer of zinc

• Heating to high temperatures

• Dipping in oil

• Mixing with mercury

What is an alloy?

• A pure metal

• A mixture of metals or a metal and a non-metal

• A type of rust

• A chemical compound

What happens to the electrical conductivity of a metal when it is alloyed?

• It becomes zero

• It decreases

• It remains the same

• It increases