can some one solve my class 10 sample paper
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34. a.Transpiration is the process of water movement through a plant and its evaporation from aerial parts, such as leaves, stems and flowers. Tiny pores called stomata is present in the leaves. It is bordered by guard cells that open and close the pore. It helps in temperature regulation. It also helps in the absorption and upward movement of water and minerals dissolved from roots to leaves. significance- 1.Cools the surface of the leaves. 2.Helps in growth and development. 3. It controls the temperature of the plants.
b. The process of movement of food from the leaves to all the other parts of the plant is known as translocation. The sieve tubes and the companion cells in the phloem of the plant involve the transport of food in plants.
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b.The action of breathing in and out is due to changes of pressure within the thorax, in comparison with the outside. This action is also known as external respiration. When we inhale the intercostal muscles (between the ribs) and diaphragm contract to expand the chest cavity. The diaphragm flattens and moves downwards and the intercostal muscles move the rib cage upwards and out.
Inhalation: This increase in size decreases the internal air pressure and so air from the outside (at a now higher pressure than inside the thorax) rushes into the lungs to equalise the pressures.
Exhalation: When we exhale the diaphragm and intercostal muscles relax and return to their resting positions. This reduces the size of the thoracic cavity, thereby increasing the pressure and forcing air out of the lungs.
35. a. The image which is formed by the convergence of light rays, and is originated from the given object, is called a Real image. We can simply say, it is the image where the light rays are actually converged. It means light rays are concentrated at that only a single point.
b. 1. concave 2. plane mirror 3. convex mirror 4.concave
c.A concave mirror produces a magnified image when the object is placed in front of the mirror:
1.between its pole and focus
2.between the focus and centre of curvature
In case 1 the image is virtual and erect, whereas in case 2 the image is real and inverted.
36.
a.Mendeleev left gaps in his table to place elements not known at the time. By looking at the chemical properties and physical properties of the elements next to a gap, he could also predict the properties of these undiscovered elements. The element germanium was discovered later.
b.(i) Position of hydrogen was not justified. (ii) Increasing order of atomic mass could not be maintained. (iii) Isotopes have similar chemical properties but different atomic masses, they cannot be given separate Places.
c.In a period, the inner core shell remains the same and the valence electrons in the valence shell go on increasing from left to right. The number of shells is the same.