6) Which of the following does not fall in the biotic component of the ecosystem? a) water
b) animals c) plants
d) grass
7) The water and the mineral ions from the soil till the tip of the plant is made availab
tube like structure called
a. Guard cell. (6) Stomata c. Xylem d. Small hole.
8) The student peeled off a green leaf and observed it under a microscope. What sha
is expected to be seen by the students?
a) Oval
b) cylindrical
c) conical
d) rectangul
9) Lack of calcium in the diet causes
a) Anemia b) simple goiter c) poor growth of bones and teeth
d) to
1

6.grass

7.xylem

8.oval

9. poor growth of bones and teetn

answer: - 3.) the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.

solution: - as per the rules, oxidation number of oxygen in its compounds is -2. the sum of oxidation numbers of all the elements of a molecule or compound is zero.

also, the oxidation number in elemental form is zero.

in no, the oxidation number of o is -2 so the oxidation number of n is +2 so that the sum is zero.

similarly, the oxidation number of c in co is +2 and o is -2.

on product side the oxidation number of n is 0 as it is in the elemental form() .

oxidation number of c in carbon dioxide is +4 as there are two oxygen in it and we know that each oxygen is -2.

so, oxidation number of n is changing from +2 to 0 and the oxidation number of c is changing from +2 to +4.

since nitrogen is reduced and hence no is acting as an oxidizing agent. carbon is oxidized and so co is acting as a reducing agent.

so, the right choice is number 3.)the oxidation state of nitrogen in no changes from +2 to 0, and the oxidation state of carbon in co changes from +2 to +4 as the reaction proceeds.