Write the name and the structural formula of the compound formed when ethanol is heated at 443 K with excess of cone. H₂SO_4. State the role of conc. H₂SO₄ in this reaction. Write chemical equation for the reaction.

"A ray of light incident on a rectangular glass slab immersed in any medium emerges parallel to itself." Draw a labelled ray diagram to justify the statement.

We often observe domestic waste decomposing in the by lanes of residential colonies. Suggest ways to make people realize that the improper disposal of waste is harmful to the environment.

Why homologous series of carbon compounds are so called? Write chemical formula of two consecutive members of a homologous series and state the part of these compounds that determines their (i) physical properties, and (ii) chemical properties.

Given below are some elements of the modern periodic table:

4 Be, 9 Fe, 14 Si, 19 K, 20 Ca

(i) Select the element that has one electron in the outermost shell and write its electronic configuration.

(ii) Select two elements that belong to the same group. Give reason for your answer.

(iii) Select two elements that belong to the same period. Which one of the two has bigger atomic size?