Full Marks 90
Question : 31 - What do you understand by functional groups in organic compounds? Write a list of various functional groups.
Answer: Functional group is an atom, or a group of atoms that has similar chemical properties whenever it occurs in different compounds. Functional groups define the characteristics physical and chemical properties of families of organic compounds. Compounds having same functional groups show similar properties. For example halo group (Chloride, fluoride, bromide). Halo group is also called halide group. Alcohol, Aldehyde, Ketone, etc. are the examples of other functional group.
Halo group: -Cl,-Br and-I is called halo group.
Aldehyde group: -CHO group is called the aldehyde group.
Ketone group: -CO- group is called ketone group.
Carboxylic acid group: -COOH group is called carboxylic acid group.
Alcohol group: -OH group is called alcohol group.
Question : 32 - What were the anomalies of Newland's Law of Octaves?
Answer: Limitation of Newlands' Octave:
At the time of Newlands; about 56 elements were known and consequently, his octaves were limited to those elements. It seems he did not expect the discovery of more elements in the future.
When elements; which were discovered later; were arranged as per the Newlands Octave; many of them did not follow the law of Newlands Octave.
Newlands Octaves could be applied up to calcium only.
Newlands put some elements together in one cell because they show similar properties. For example; he put cobalt (Co) and nickel (Ni) in one cell together. This created lot of confusion.
Iron was kept apart from cobalt and nickel while all these three elements have similar properties.
The above mentioned and many other anomalies made the Newlands' Law of Octaves limited to certain elements and finally his Law of Octaves could not be considered relevant even for many elements known during his time.
Question : 33 - With the help of suitable diagram, explain the structure of female human reproductive system.
Answer: The Female Reproductive System
The female reproductive system in humans is composed of two main parts. One part is responsible for production of eggs and another part is responsible for development of the embryo. There are following main parts in the female reproductive system.
Uterus: It is hollow tube-like muscular organ which somewhat resembles the shape of a pear. The embryo gets implanted on the wall of the uterus and further development of the embryo happens inside the uterus.
Ovary: There is one ovary on each side of the uterus. Ovaries serve two purposes, i.e. production of eggs and secretion of the female hormones oestrogen and progesterone. The female hormones play an important role in the reproductive cycle and also bring out the secondary sexual characters in females. All the eggs in a female are manufactured while the girl child is still inside the womb. But these eggs are immature. One egg matures during each menstrual cycle and the process is called ovulation.
Fallopian tubes: These are two tube-like extensions coming out laterally from the top portion of the uterus. There are finger-like structures at the end of the fallopian tubes. These structures are called fimbriae or the funnel of the oviduct. Fallopian tube is also known as oviduct. During ovulation, a mature egg passes into the fallopian tube.
Vagina: It is a muscular tube which continues from the lower portion of the uterus to outside. The lower portion of the uterus is called the mouth of the uterus or cervix. Vagina provides passage to the sperms and also to the fully developed baby. Due to this, the vagina is also known as 'birth canal'. In females the vaginal opening and the urethral opening are separate.
Question : 34 - What are the disadvantages of a large population? Suggest various methods of population control.
Answer: A large population presents many challenges. Limited amount of natural resources; especially the land for agriculture; means it would be very difficult to provide food for a large population. Managing a big family can be a big problem for the bread earner of the family. For the society also, a large population creates pressure on various resources.
Methods of Contraception
Methods of contraception help in preventing pregnancy and thus in restricting the family size. The methods of contraception are given below.
Question 35 - The focal length of a convex lens is 20 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 = - 20 cm and u = - 30 cm.
We can find the image distance by using the lens formula:
Thus, the object distance is -12 cm; the negative sign shows that the image if formed on the same side of the lens.
Magnification can be calculated as follows:
The positive sign shows that the image is erect and virtual.
Question 36 - You are given a convex lens but you do not know its focal length. Describe an activity by which you will find the focal length of the given convex lens.
Answer: For finding the approximate focal length of a given convex lens, we need following materials:
A lens stand, a ruler and a screen.
Select a distant object which is well lit by the sunlight. A tree or an electric pole can be ideal for this purpose.
Keep the screen in erect position.
Keep the lens between the object and the screen.
Adjust the distance between the screen and the lens so that you can get a clear image of the distant object on the screen.
The distance between the lens and the screen gives the approximate value of focal length of the given convex lens.
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