Board � Central Board of Secondary Education, cbse. A and You are to attempt both the sections. However, internal choice has been provided in two questions of three marks each and one.
Only one option in. These are to be answered in one word or in one sentence. These are to be answered in about 30 words each. These are to be answered in about 50 words each.. These arc to be answered in about 70 words each. These are to he answered in brief. Question 1: If on a round trip you travel 6 km and then arrive back home, calculate your displacement after completing the trip.
Answer: Displacement is zero. Question 2: The atomic number of three elements A, B and C are 9,10 and 13 respectively. Which of them will form a cation? Answer: The element with atomic number 13 will form a cation. It has the electronic configuration 2, 8, 3. It loses three electrons to attain stable octet and forms the cation. Question 3: i What is the similarity in the electronic structure of the following set of atoms : a Lithium b Sodium c Potassium ii Which of the above elements is most reactive and why?
Answer: i Electronic configuration of the elements are given as under:. Question 4: What are Phanerogams? Point out differences between its two groups. Phanerogams are flowering plants. Its two groups are Gymnosperms and Angiosperms: Answer:. Question 5: Why are antibiotics effective against bacteria but not against viruses? Answer: Antibiotics act by preventing one of the bio-chemical events towards formation of a new pathogen cell. Thus, most antibiotics prevent cell wall formation, which happens in bacterial cell only, thereby preventing bacterial diseases.
Question 6: a Write four phenomena which were successfully explained using universal law of gravitation. How should the distance between the objects be changed so that force between them becomes 50 N?
Answer: a The universal law of gravitation successfully explained several phenomena. Some such phenomena are: i the force which binds us to the earth ii motion of moon around Byjus Class 9 Maths Sample Paper Set 3 Solutions Singapore the earth iii motion of planets around the sun iv occurrence of sea tides Byjus Class 6 Maths Sample Paper Vol due to attraction of moon and of sun. Then as per inverse square law, we have. Question 7: Give reason for the following : a The sound of a thunder is heard a little later than the flash of light is seen, b The ceilings of the concert hall are curved.
Answer: a In lightning process, flash and thunder are produced simultaneously. It is done to ensure that the sound after reflection from the ceilings reaches all corners of the hall. Some animals, who are sensitive to infrasonic waves, get disturbed due to them. Question 8: The velocity-time graph of an object is shown in the figure.
Give reason for your answer. Question 9: a Suggest two ways to decrease pressure on a surface. Answer: a Two suggested ways so as to decrease pressure on a surface are : decrease the force acting on the surface, and increase the surface area of given surface.
Density of an object in CGS system is d � 1. Question a Define atomicity. Atomicity of the substances is given as under:. Find the valencies of X and other element present in the compound. Question a How are CFCs harmful for the environment and living beings? Answer: a CFCs result in damaging the ozone layer.
This results in global warming. This has resulted in increased number of skin cancer. Question i Write the definition of health as given by WHO. Answer: i According to WHO, health is a state of complete physical, mental and social well being, and not merely an absence of disease or infirmity.
Explain the basis of Principle of Treatment for any disease. Answer: There are two ways to treat an infectious disease. They are as follows : i Reduce the effect of disease : The principle involved is that the effect of disease is lessened without killing the infectious agent which is done either by taking medicines and antibiotics as well as taking appropriate rest so that the body heals.
These processes may be pathways for respiration or synthesis of new substances. Drugs are available which block these processes and kill the infectious agents. Antibiotics are chemicals produced by microbes which kill or prevent the growth of other microbe by blocking life processes without harming human cells. Question Ravi is a poor labourer. For last few days he used to feel pain in his lower abdomen as well as in his back.
When he went to a doctor, the doctor prescribed some clinical tests as well as ultrasonography of lower abdomen. When Rita, who lived nearby came to know of this, she decided to give financial help to Ravi. After tests and ultrasonography it was found that there was a stone in the left kidney of Ravi. Rita asked her neighbours to contribute for the operation.
All the neighbours contributed for the operation as well as subsequent medical expenses. Now Ravi is absolutely fit. Explain its working principle. Answer: i Ultrasound is a diagnostic technique, used to get images of internal organs. It is based on the principle called piezoelectric pressure electricity effect.
Question a How would you arrive at a mathematical formula to measure force using second law of motion? Define the unit of force using this formula. Calculate the distance of penetration of the bullet into the block. Also, calculate the magnitude of the force exerted by the wooden block on the bullet. Let an object of mass m was initially moving with a velocity u. Question a Define work. Give SI unit of work done. Write an expression for positive work done. Also state the type of work done. Answer: a Work done on an object is defined as the magnitude of the force acting on the object multiplied by the distance moved by the object in the direction of the applied force.
SI unit of work is called joule J or N m. Work is said to be 1 joule if under the influence of a force of 1 N the object moves through a distance of 1 m along the direction of applied force. Give an expression for gravitational potential energy. What is the power supplied by the crane? Question Wet clothes dry up similarly when we spill water on the floor it dries up after sometime. In both the cdses change of state from liquid to vapour takes place without reaching the boiling point.
Answer: i This phenomenon is called evaporation. This is how evaporation takes place. Rahul told her that he can separate the mixture. Name the technique used by Rahul and explain how he will do. Draw the diagram and write the principle of this technique.
Answer: The technique used by Rahul to separate the mixture of oil and water was to use separating funnel as shown in figure. Kerosene oil does not mix with water and forms a separate layer. Oil being lighter than water, forms the upper layer. Steps involved in the separation of kerosene oil from water are: i Pour the mixture of kerosene oil and water in the separating funnel.
Let it stand undisturbed for sometime so that separate layers of oil and water are formed. Question The immune system Byjus Class 12 Maths Sample Paper University of Hari is damaged by the attack of pathogen on his body. Question Answer the following � i Draw a labelled diagram of smooth muscle.
Answer: i ii Distinction between parenchyma and sclerenchyma on the basis of their cells wall:. Cells are loosely packed with large intercellular spaces and form the packing tissue of all plant organs. It also facilitates movement of gases. Parenchyma cells remain turgid and provide rigidity to softer parts. The walls are thick on all sides due to presence of lignin.
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