Q1 of 58 Page 1

The atomic numbers of three elements A, 8 and C are 11, 17 and 19 respectively. State giving reason which out of two elements will show similar chemical properties.

The electronic configuration of the elements will be as follows:

A: 2,8,1


B: 2,8, 7


C: 2,8, 8,1


Since elements A and C have same no. of valence electrons i.e. 1, so they will show similar chemical properties.


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16

A student focused the image of an object on a white screen using a converging lens. He noted down the positions of the object, screen and the lens on a scale as given below: Position of object= 10.0 cm

Position- of lens = 50.0 cm


Position of screen= 90.0 cm


(a) Find the focal length of the converging lens.


(b) Find the position of the image if the object is shifted towards the lens at a position of 30.0 cm.


(c) State the nature of the image formed if the object is further shifted towards the lens.

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List the sign conventions that are followed in case of refraction of light through spherical lenses. Draw a diagram and apply these conventions in determining the nature and focal length of a spherical lens which forms a four times magnified, real image of an object placed 20 cm from the lens.

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Name the body part where fertilization occurs in human female.

 3

Write the main objective of conservation of biodiversity.