What is meant by the 'calorific value' of a fuel? How is it determined? Arrange the following fuels in a decreasing order of their calorific values: Kerosene, Coal, LPG.

Lithium, sodium and potassium form a Dobereiner's triad. The atomic masses of lithium and potassium are 7 and 39 respectively. Predict the atomic mass of sodium.

Why are the small numbers of surviving tigers a cause of worry from the point of view of genetics?

A person can comfortably read a book, but finds difficult to read the number on a bus parked 5m away from him.Name the type of defect of vision he is suffering from.Which type of lens should he use in his spectacle to correct his vision?

Can away source energy be pollution free? Why or why not?

What is ethanoic acid? Write the formula of the functional group present in this acid. What special name is given to its 5-8% solution in water? How does ethanoic acid react with sodium carbonate? Write a chemical equation of the reaction and common name of the salt produced.

(i)What is fertilisation?Distinguish between external fertilisation and internal fertilisation
(ii)What is the site of fertilisation in human beings?

Only variations that confer an advantage to an individual organism will survive in a population. Do you agree with this statement? Why or why not?

What is lens formula?

What eye defect is Myopia?Describe with a neat diagram how this defect of vision can be corrected by using suitable lens?

How 'respiration' different from 'breathing'? Explain the processes of 'aerobic' respiration and 'anaerobic' respiration.

Describe the central nervous system in human being under the following heads:
(i) Regions included
(ii) Three functions of any one region

(a) What are 'magnetic field lines'? How is the direction of a magnetic field at a point determined?
 (b) List any three properties of magnetic field lines.
 (c) Draw two field lines around a bar magnet along its length on its two sides and mark the field directions on them by arrow marks.

(a) State one limitation of solar energy available from solar cells.
(b) What is the minimum wind velocity required to obtain useful energy with a windmill?
(c) Define the term 'nuclear fission'.

A dry pellet of a common base B, when kept in open absorbs moisture and turns sticky.  The compound is also a by-product of chlor-alkali process.  Identify B.  What type of reaction occurs when B is treated with an acidic oxide?  Write a balanced chemical equation for one such solution.

Draw the diagram of alimentary canal of man and label the following parts.
Mouth, Oesophagus, Stomach, Intestine

(a) Give a chemical test do distinguish between saturated and unsaturated hydrocarbon.
(b) Name the products formed when ethane burns in air. Write the balanced chemical equation for the reaction showing the types of energies liberated.
(c) Why is reaction between methane and chlorine in the presence of sunlight considered a substitution reaction?

(a) In this ladder (Figure) symbols of elements are jumbled up. Rearrange these symbols of elements in the increasing order of their atomic number in the Periodic Table.
(b) Arrange them in the order of their group also.

Define evolution. How does it occur? Describe how fossils provide us evidences in support of evolution.

Explain the structure and functioning of Human eye.How are we able to see nearby as well as distant objects?

(a) What is 'environmental pollution'?
(b) Distinguish between biodegradable and non-biodegradable pollutants.
(c) Choose the biodegradable pollutants from the list given below:
Sewage, DDT, radioactive waste, agricultural waste.

In the context of conservation of natural resources, explain the terms reduce, recycle and reuse. From among the materials that we use in daily life, identify two materials for each category.