10th Science Paper Solutions Set 1 : CBSE All India Previous Year 2009

General Instructions:
(i) The question paper comprises of two sections, A and B. You are to attempt both the sections
(ii) All questions are compulsory
(iii) There is no overall choice. However, internal choice has been provided in all the three questions of five marks category. Only one option in such questions is to be attempted
(iv) All questions of Section A and all questions of Section B are to be attempted separately
(v) Questions number 1 to 6 in Section A and 17 to 19 in Section B are short answer type questions. These questions carry one mark each
(vi) Questions number 7 to 10 in Section A and 20 to 24 in Section B are short answer type questions and carry two marks each
(vii) Questions number 11 to 14 in Section A and 25 and 26 in Section B are also short answer type questions and carry three marks each
(viii) Questions number 15 and 16 in section A and question number 27 in section B are long answer type questions and carry five marks each
Q1 :

In electrolysis of water, why is the volume of gas collected over one electrode double that of gas collected over the other electrode?


Answer :

The balanced chemical equation for the electrolysis of water is:

It can be observed from the balanced chemical equation that the volumes of hydrogen and oxygen produced during electrolysis are in the ratio 2: 1. Thus, the volume of hydrogen gas collected in the process is double than that of oxygen.

Q2 :

What effect does an increase in concentration of H+ (aq.) in a solution have on the pH of solution?


Answer :

The pH of the solution is indirectly proportional to the concentration of H+ ions. Hence, with an increase in the concentration of H+ (aq.) in a solution, the pH of the solution will decrease.

Q3 :

What happens when a small piece of sodium is dropped into ethanol?


Answer :

When a small piece of sodium is dropped into ethanol, sodium reacts with ethanol to give sodium ethoxide. Hydrogen gas is evolved in the process. This reaction can be represented by the following equation.

Q4 :

Draw a schematic diagram of an electric circuit consisting of a battery of two cells each of 1.5 V, 5 Ω, 10 Ωand 15 Ωresistors and a plug key, all connected in series.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q5 :

When is the force experienced by a current-carrying conductor placed in a magnetic field the largest?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q6 :

State the rule which gives the direction of magnetic field associated with a current-carrying conductor.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q7 :

(i) Name the products formed when sodium hydrogen carbonate is heated.

(ii) Write the chemical equation for the reaction involved in the above.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q8 :

(i) What is observed when a solution of potassium iodide is added to a solution of lead nitrate taken in a test tube?

(ii) What type of reaction is this?

(iii) Write a balanced chemical equation to represent the above reaction.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q9 :

What is an electric circuit? Distinguish between an open and a closed circuit.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q10 :

Calculate the resistance of an electric bulb which allows a 10 A current when connected to a 220 V power source.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q11 :

(a) What is meant by periodicity in properties of elements with reference to the periodic table?

(b) Why do all the elements of the same group have similar properties?

(c) How will the tendency to gain electrons change as we go from left to right across a period? Why?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q12 :

(a) Distinguish between esterification and saponification reactions of organic compounds.

(b) With a labelled diagram describe an activity to show the formation of an ester.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q13 :

For which position of the object does a convex lens form a virtual and erect image? Explain with the help of a ray diagram.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q14 :

(a) Define the term ‘volt’.

(b) State the relation between work, charge and potential difference for an electric circuit.

Calculate the potential difference between the two terminals of a battery if 100 joules of work is required to transfer 20 coulombs of charge from one terminal of the battery to the other.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q15 :

(a) Distinguish between ionic and covalent compounds under the following properties:

(i) Strength of forces between constituent elements

(ii) Solubility of compounds in water

(iii) Electrical conduction in substances

(b) Explain how the following metals are obtained from their compounds by the reduction process:

(i) Metal M which is in the middle of the reactivity series.

(ii) Metal N which is high up in the reactivity series.

Give one example of each type

OR

(a) Distinguish between ‘roasting’ and ‘calcination’. Which of these two is used for sulphide ores and why?

(b) Write a chemical equation to illustrate the use of aluminium for joining cracked railway lines.

(c) Name the anode, the cathode and the electrolyte used in the electrolytic refining of impure copper.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q16 :

(a) What is dispersion of white light. What is the cause of such dispersion. Draw a diagram to show the dispersion of white light by a glass prism.

(b) A glass prism is able to produce the spectrum when white light passes through it, but a glass slab doesn’t produce any spectrum. Explain why it is so. 


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q17 :

Which compounds are responsible for the depletion of ozone layer?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q18 :

Why is DNA copying an essential part of the process of reproduction?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q19 :

Where does digestion of fat take place in our body?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q20 :

How is charcoal obtained from wood? Why is charcoal considered a better fuel than wood?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q21 :

Describe how hydro-energy can be converted into electrical energy. Write any two limitations of hydro-energy.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q22 :

What is Chipko movement? Why should we conserve forests?


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q23 :

Suggest any four changes that you would like to be incorporated in the life-style of students of your age to move towards a sustainable use of available resources.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q24 :

Describe the role of the following in human beings:

(i) Seminal vesicles

(ii) Prostate gland


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q25 :

What is ‘Phototropism’? How does it occur in plants? Describe an activity to demonstrate phototropism.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q26 :

Explain how the sex of the child is determined at the time of conception in human beings.


Answer :

Please Register/Login to get access to all solutions Facebook Login
Q27 :

(a) Draw a sectional view of the human heart and label on it Aorta, Pulmonary arteries, Vena cava, Left ventricle.

(b) Why is double circulation of blood necessary in human beings?

 


Answer :

Please Register/Login to get access to all solutions Facebook Login

10th Science Paper Solutions Set 3 : CBSE Delhi Previous Year 2013 will be available online in PDF book soon. The solutions are absolutely Free. Soon you will be able to download the solutions.