11.

List two tests for experimentally distinguishing between an alcohol and a carboxylic acid and describe how these tests are performed.

Draw the electron-dot structure for ethyne. A mixture of ethyne and oxygen is burnt for welding. In your opinion, why cannot we use a mixture of ethyne and air for this purpose ?

Two elements ‘P’ and ‘Q’ belong to the same period of the modern periodic table and are
in Group 1 and Group 2, respectively. Compare their following characteristics in tabular form:

(a) The number of electrons in their atoms

(b) The sizes of their atoms

(c) Their metallic character

(d) Their tendencies to lose electrons

(e) The formula of their oxides

(f) The formula of their chlorides

Taking the example of an element of atomic number 16, explain how the electronic configuration of the atom of an element relates to its position in the modern periodic table and how valency of an element is calculated on the basis of its atomic number.

Both soap and detergent are some type of salts. What is the difference between them? Describe in brief the cleansing action of soap. Why do soaps not form lather in hard water? List two problems that arise due to the use of detergents instead of soaps.

When you add sodium hydrogen carbonate to acetic acid in a test tube, a gas liberates immediately with brisk effervescence. Name this gas. Describe the method of testing this gas.

The absolute refractive indices of glass and water are 4/3 and 3/2, respectively. If the speed of light in glass is 2 × 10⁸m/s, calculate the speed of light in,

a) vacuum
b) water

What is meant by scattering of light? Use this phenomenon to explain why the clear sky appears blue or the Sun appears reddish at sunrise?

Name the life process of an organism that helps in the growth of its population