Full Marks 90
Question: 19 - Write the chemical structure of acetic acid.
Question: 20 - Comment on oxygen's position in Modern Periodic Table.
Answer: The atomic number of Oxygen is 8 and its electronic configuration can be written as follows:
O (8): 2, 6
There are 6 electrons in the last orbit, hence Oxygen belongs to Group 6.
There are two shells in oxygen atom, hence Oxygen belongs to second period.
Question: 21 - Draw well labeled diagram to show the structure of sperm.
Question: 22 - What are the advantages of cross pollination?
Answer: Cross pollination has following advantages:
Question: 23 - What are the advantages of asexual reproduction?
Answer: Advantages of asexual reproduction:
Question: 24 - With the example of homologous organs, show that a human and a bird have common ancestor.
Answer: Forelimbs of birds and humans are examples of homologous organs. Both of them are similar in design. The forelimbs of both birds and humans are composed of humerus and radio-ulna. But forelimbs of human beings are used for handling tools, while the forelimbs of birds are used for flying. Thus, their functions are entirely different in birds and humans. The similar design shows that birds and humans have evolved from a common ancestor.
Question: 25 - A spherical lens works on which phenomenon? Give a brief explanation of this phenomenon.
Answer: A spherical lens works on refraction of light. When a ray of light travels from one medium to another; there is a change in its path. This happens due to difference in optical densities of two media. This phenomenon is called refraction of light.
Question: 26 - The focal lengths of two convex lenses are 20 cm and 30 cm; respectively. Find the power of a system which uses the combination of these two lenses.
Answer: We have; f1 = +20 cm = +0.2 m and f2 = +30 cm = +0.3 m
Power of first lens = 1/f1 = 1/0.2 = +5 D
Power of second lens = 1/f2 = +3.33 D
Power of combination of lenses = 5 + 3.33 = +8.33 D
Question: 27 - Draw a diagram to show the formation of image by convex lens when the object is kept at between infinity and 2F of a convex lens.
Question: 28 - A concave mirror can be used in a solar cooker. Why?
Answer: A concave mirror is also known as a converging mirror because rays of light converge at focus after getting reflected from a concave mirror. Due to this, the solar energy can be concentrated at focus of the concave mirror. This can help in producing more heat. Hence, a concave mirror can be used in solar cooker.
Question: 29 - What are the disadvantages of wind energy?
Answer: Disadvantages of wind energy:
Question: 30 - Write some steps by which you can reuse certain items to conserve the resources.
Answer: Following items can be reused to conserve resources:
Question: 31 - What is combustion reaction? Explain with the example of any three organic compounds.
Answer: A reaction in which a material gets oxidized and heat and light are produced in the process is called combustion reaction. Organic compounds undergo combustion and produce heat and light. Some of the reactions involving organic compounds are given below:
Question: 32 - What were the drawbacks of Doberiener's Triads? How the Newland's Law of Octaves was better than Doberiener's Triads?
Answer: Drawbacks of Doberiener's Triads:
Dobereiner could find only three such triads (group of three elements) and he could not even put all the elements known at that time in his triads.
The rules of Dobereiner's triads could not be applied to the elements which had very low or high atomic mass. Such as; if F, Cl and Br are put together in a triad, in increasing order of their atomic masses, the atomic mass of Cl is not an arithmetic mean of atomic masses of F and Br.
Newland's Law of Octave was better from Doberiener's triads in many ways. Newland arranged elements in order of their increasing masses and found some pattern in their properties.
Compared to Doberiener's attempts, more elements could be put in Newland's arrangement.
Question: 33 - With the help of a suitable diagram, explain the process of metamorphosis in frog.
Answer: The young ones of frogs are called tadpoles. They don't look like adult frogs rather resemble more to a fish. They have a tail and they breathe through gills. During metamorphosis, the tail is shed off and gills disappear. The adult frog uses skin to breathe under water and uses lungs to breathe on land.
Image Ref: http://upload.wikimedia.org/wikipedia/commons/a/ae/Metamorphosis_frog_Meyers.png
Question: 34 - A person is about 45 years old and has two children. He wants to use some contraceptive method. Suggest a suitable method for that person. Give reasons for your answer.
Answer: A 45 years old person who has two children would; in all likelihood; would not like to have more children. So, the person should be advised to go for permanent contraceptive method. He should go for tubectomy or vasectomy. We know; that vasectomy is performed on men in which the vas deferens is either tied or cut off. On the other hand, tubectomy is performed on women in which fallopian tube is either tied or cut off.
The person should opt for vasectomy because this is much safer than tubectomy. Moreover, contrary to popular beliefs, vasectomy does not result in any loss of vigour for the man. Many sociologists are also of the view that instead of putting all the burden on the woman, the man should be proactive in applying a particular method contraception.
Question: 35 - The focal length of a concave mirror is 15 cm. The object is at a distance of 30 cm from the lens. Find the image distance. Also write the nature of the image thus formed.
Answer: We have f = -15 cm and u = - 30 cm
We can calculate image distance by using following formula:
Since; we get negative value, hence image is real and inverted.
Question: 36 - Write the steps by which you can find the approximate focal length of a concave mirror.
Answer: For finding the approximate focal length of a concave mirror, we need to take following steps:
Class ten Science - Sample Paper - (2) for SA - 2 - Part - II will be available online in PDF book form soon. The solutions are absolutely Free. Soon you will be able to download the solutions.