Physical And Ch...

A man painted his main gate that was made of iron. This is done in order to

(i) prevent it from rusting
(ii) protect it from the sunlight
(iii) make it look beautiful
(iv) make it dust free

Which of the above reasons is/are correct?

Corrosion is a chemical reaction that involves

During an activity, following three test tubes are set up:

Test tube 1: A shiny iron nail is placed in a test tube along with anhydrous calcium chloride. Mouth of the test tube is covered with cotton wool.
Test tube 2: A test tube is filled with boiled water and a shiny nail is dropped in it. A layer of oil is placed on the surface of water.
Test Tube 3: A test tube is filled with tap water and a shiny iron nail is dropped in it. The test tube is left open.

In which of the test tubes will rusting not take place when observed after a week?

Identify the incorrect statement(s).

Statement I: All physical changes are spontaneous, but chemical changes have to be induced.
Statement II: All changes, physical as well as chemical, involve energy exchanges.

Zinc oxide (ZnO) reacts with carbon (C) to produce zinc (Zn) and carbon monoxide (CO). The balanced chemical equation for the given reaction is ZnO (s) + C (s) → Zn (s) + CO (g). Which of the following substances is reduced in the given reaction?

Which of the following statements is not true about a substance that goes rancid?

Which of the following phenomena is not an indication of a chemical change?

The substances which prevent oxidation of food are called