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CBSE Class 10 Science Solved Question Paper 2016

Long Answer Type

31.

a) Give a chemical test to distinguish between saturated and unsaturated hydrocarbon.

b) Name the products formed when ethane burns in the air. Write a balanced chemical equation for the reaction showing the types of energies liberated.

c) Why is the reaction between methane and chlorine in the presence of sunlight considered a substitution reaction?

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32.
(a) Define the following terms in the context of spherical mirrors:

i) Pole

ii) Centre of curvature

iii) Principal axis

iv) Principal focus
b) Draw ray diagrams to show the principal focus of a

i) concave mirror
ii) convex mirror

c) Consider the following diagram in which M is a mirror and P is an object and Q is its magnified image formed by the mirror.

State the type of mirror and one characteristic property of the image Q.

a)

i) Pole: A pole is the central point of the reflecting surface of a spherical mirror. Pole lies on the mirror and is denoted by P.

ii) Centre of curvature: The centre of a sphere from which the given spherical mirror (convex or concave) is obtained is called as centre of curvature.

It is denoted by the letter C.

iii) Principal axis: An imaginary straight line passing through the pole and centre of curvature is termed as the principal axis.

iv) Principal focus: The focus (F) is the point on the principal axis of a spherical mirror where all the incident rays parallel to the principal axis meet or appear to diverge from after reflection.

b)

Concave mirror: The focus lies on the same side of the reflecting surface.

Convex mirror: Focus is obtained on the opposite side of the reflecting surface by extending the rays reflected from the surface of the mirror.

c)

The given mirror M is a concave spherical mirror. The image formed is a virtual image and it is the characteristic property of the image.

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33. (a) Draw a ray diagram to show the formation of an image by a convex lens when an object is placed in front of the lens between its optical centre and principal focus.

(b) In the above ray diagram, mark the object distance (u) and the image distance (v) with their proper signs (+ve or –ve as per the new Cartesian sign convention) and state how these distances are related to the focal length (f) of the convex lens in this case.

(c) Find the power of a convex lens which forms a real and inverted image of magnification –1 of an object placed at a distance of 20 cm from its optical centre.

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34. (a) Write the function of each of the following parts of the human eye:

Cornea; iris; crystalline lens; ciliary muscles

(b) Millions of people in the developing countries of the world are suffering from corneal blindness. These persons can be cured by replacing the defective cornea with the cornea of a donated eye. A charitable society of your city has organised a campaign in your neighbourhood in order to create awareness about this fact. If you are asked to participate in this mission, how would you contribute in this noble cause?

(i) State the objective of organising such campaigns.

(ii) List two arguments which you would give to motivate the people to donate their eyes after death.

(iii) List two values which are developed in the persons who actively participate and contribute in such programmes.

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35.

(a) Write the functions of the following parts in human female reproductive system:

(i) Ovary
(ii) Oviduct
(iii) Uterus

(b) Describe the structure and function of placenta.

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36.

What is meant by speciation? List four factors that could lead to speciation. Which of them cannot be a major factor in the speciation of a self pollinating plant species. Give reason to justify your answer.

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