Here, we are going to share Class 10th Board exam Paper with solutions of Science (Code 086) Set 1 conducted on 3rd March 2015.


The question paper is divided into two section A and B with total of 36 questions. Below is the sample of question with solutions. You can download whole paper via below link given.

Section A

1. Write the number of Covalent bonds in the molecule of ethane.
► 7 (C2H6, Six C-H bonds and one C-C bonds)

2. Name the life process of an organism that helps in the growth of its population.
► Reproduction

3. What will be the amount of energy available to the organisms of the 2nd trophic level of a food chain if the energy available at the first trophic level is 10,000 joules?
► 1,000 Joules (Apply 10% law of energy transfer, 1,000 is 10% of 10,000)

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


Note: In the given question, the refractive indices of glass and water are wrong. The question is solved accroding to correct values.

5. List two main causes of the pollution of water of the river Ganga. State how pollution and contamination of river water prove harmful for the health of the people of neighbouring areas.


Two main causes of the pollution of water of the river Ganga are:
(i) Release of industrial waste into it.
(ii) Dumping of untreated sewage.
The people of neighbouring areas use river water for domestic or drinking purpose either by directly or through pipelines. Ultimately, contaminated water leads to severe health diseases such as typhoid or cholera.

6. What is biodiversity? What will happen if biodiversity of an area is not preserved? Mention one effect of it.


The variety of living organisms living in a particluar area constitutes its biodiversity.
If the biodiversity is not preserved then it can result in environmental disasters such as floods, forest fires and hurricanes.

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


Carboxylic acid can be distinguished from an alcohol by performing the following tests:
(i) Litmus Test: Take 2 ml of alcohol and a carboxylic acid in test tubes. Put 1 or 2 drop of blue litmus solution into each test tube. The liquid which show no effect is alcohol and liquid which turns red is carboxylic acid.
(ii) Sodium hydrogen carbonate test: When a solution of baking soda is treated with a few drops of a carboxylic acid, brisk effervescence is observed due to the evolution of carbon dioxide gas. When this gas is passed in lime-water, the later turns milky. Whereas no effervescence occurs upon treating an alcohol with baking soda solution.

8. 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?


Ethyne burns in air with a sooty flame because of incomplete combustion caused by the limited supply of air. However, ethyne burns in oxygen with a clean flame with a temperature of 3000 C because of complete combustion. This oxy-acetylene flame is used for welding. Such a high temperature cannot be achieved without mixing oxygen. Therefore, a mixture of ethyne and air is not used for welding.

You can download full solutions in PDF via link given below:

Download Science (Set 1) board paper with solutions 2015
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