CBSE Pathshala

CBSE CLASS CHAPTER NO.15 SOME NATURAL PHENOMENA:Question Banks 1. How many types of charges exist? a. One b. Three c. Two d. Four 2. Who invented the lightning conductor? a. Alexander Fleming b. Graham Bell c. Benjamin Franklin d. Thomas Alva Edison 3. What device is used to protect building from lightning? a. Crescograph b. Anemometer c. Lightning Conductor d. Barometer 4. What scale is used to measure the magnitude of earthquake? a. Richter b. Celsius c. Fahrenheit d. Kilogram 5. The magnitude of earthquakes that occurred at Bhuj and Kashmir were a. less than 4 b. less than 2 c. less than 6 d. Higher than 7 6. Name 2 natural phenomena which cause us heavy damage. 7. Why were the people of ancient times afraid of lightning? 8. What is lightning due to? 9. What was the discovery made by Ancient Greeks? 10. List two daily life examples where charges are produced. 11. What are charged objects? 12....

What is meant by reproduction? The process of producing new individuals of same kind of the same species is called reproduction. Why reproduction is a essential life process? Reproduction is essential for continuation of the species from generation to generation. What are the different modes of unisexual reproduction? The modes of reproduction evolve only one parent is called unisexual reproduction. (a) Fission: The mode of reproduction in which unicellular organism split into two equal halves and produce new ones is called binary fission. For example amoeba and bacteria (b) Fragmentation : The mode of reproduction in which body of plant breaks up into smaller fragments and each fragment grows into a new individual is known as Fragmentation e.g. Spirogyra , algae (c) Budding : The mode of reproduction in which small buds when develop get separated and mature into new organisms is called Budding. E.g. Yeast, Hydra, Bryophyllum (d) Spore formation : The m...

Extra score Questions Q. Can any object have mechanical energy even if its momentum is zero? Explain. Ans: Yes, mechanical energy comprises of both potential energy and kinetic energy. Zero momentum means that velocity is zero. Hence, there it no kinetic energy but the object may possess potential energy. Q.   Can kinetic energy of a body be negative? Ans: No, It is because mass and velocity cannot ne negative Q. A freely falling object eventually stops on reaching the ground. What happens to its kinetic energy? Ans: A freely falling object just before hitting the ground has maximum kinetic energy. After falling, it rolls on the rough ground and finally comes to rest. The kinetic energy of the object is used up in doing work against friction; which finally appears as heat energy. Q. A light and a heavy object have the same momentum find out the ratio of their kinetic energies. Which one has a larger kinetic e...

Q.1. Why does silicon is classified as Metalloid? Ans: Silicon  is gray color solid at room temperature with very high melting point and boiling point that lose or gain 4 electrons [   3s 2 , 3p 2 ] having both metallic and non metallic properties so it is classified as Metalloid eg. Sio 2 Q.2.Why inert gases have zero valencies? Ans: It is because Inert gases have 2 or 8 electrons in valence shell. Q.3. How is valency of an element determined? Ans: The valency of an element measures its ability to combine with other elements. The valency is determined by knowing place in periodic table. . All the elements in group VIII have eight electrons in their outer shells, and thus have a valency of zero (highly stable). Elements in group I just have one valence electron in their outer shells and thus have a valency of one. Q.4. why could no fixed position be given to hyderogen in Mendleev’s Periodic table? Ans: Hydrogen placed in the first column above ...

Chapter – 11 The Human Eye and the  Colorful  World Q 1. What is meant by power of accommodation of the eye? Ans. The ability of the eye lens to adjust its focal length, so as to clearly focus rays coming from distant as well a near objects on the retina, is called the power of accommodation of the eye. Q2. A person with a myopic eye cannot see objects beyond 1.2 m distinctly. What should be the type of the corrective lens used to restore proper vision? Ans. A person with a myopic eye should use a concave lens of focal length 1.2 m so as to restore proper vision. Q 3. What is the far point and near point of the human eye with normal vision? Ans. For a human eye with normal vision the far point is at infinity and the near point is at 25 cm from the eye. Q 4. A student has difficulty reading the blackboard while sitting in the last row. What could be the defect the child is suffering from? How can it be corrected? Ans. The student is suffering from myopia...