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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.

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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.

(a) i . Ovary - They produce eggs or the female gamete. They also prodece the female hormone estrogen which brings about the development of secondary sexual characters in females.

(ii) Oviduct - Carries the mature egg to the uterus. The oviduct provide the place for fertilisation to occur.

(iii) Uterus - It nurturing the fertilized ovum that develops into the fetus and holding and supporting it till the baby is mature enough for birth.

(b) Placenta is a disc which is embedded in the uterine wall. It contains villi on the embryo’s side of the tissue. On the mother’s side are blood spaces, which surround the villi.

Th placenta provides a large surface area for glucose and oxygen to pass from the mother to the embryo. The waste substances generated by the foetus is removed by transferring them into the mother’s blood through the 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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