11.

Write chemical equation of the reaction of ethanoic acid with the following:
a) Sodium
b) Sodium hydroxide
c) Ethanol

What happens when a mature spirogyra filament attains considerable length?

The depletion of ozone layer is a cause of concern. Why?

An aldehyde, as well as ketone, can be represented by the same molecular formula say C₃H₆O, Write their structures and name them. State the relation between the two in the language of science.

What was Chipko Andolan? How did the Andolan ultimately benefit the local people and the environment?

An element 'X' belongs to 3rd period and group 16 of the Modern periodic table.

a) Determine the number of valence electrons and the valency of 'X'

b) Molecular formula of the compound when 'X' reacts with hydrogen and write its electron dot structure.

c) Name the element 'X' and state whether it is metallic or non-metallic.

Burning of fossil fuels results in global warming. Give reasons to justify this statement. 

An element 'X' has mass number 35 and a number of neutrons 18. Write atomic number and electronic configuration of 'X'.Also write group number,period number and valency of 'X'

A carbon compound 'P' on heating with excess conc. H₂SO₄ forms another carbon compound 'Q' which on the addition of hydrogen in the presence of nickel catalyst forms a saturated carbon compound'R'. One molecule of 'R' on combustion forms two molecules of carbon dioxide and three molecules of water. Identify p,Q and R and write chemical equations for the reactions involved.

Define reproduction.  How does it help in providing stability to the population of species?