Q5 of 27 Page 1

Define the term power of accommodation. Write the modification in the curvature of the eye lens which enables us to see the nearby objects clearly?

The ability of the eye lens to change its focal length is known as the power of accommodation. The ciliary muscles present in the eye change the curvature of the lens which in turn change the focal length of the lens. To see nearby objects clearly, the focal length of lens should be less than that for seeing objects at normal distance. The ciliary muscles contract and cause the lens to become thicker. A thicker lens will have a decreased focal length than a normal sized lens so nearby objects will be visible.


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3

How it can be proved that the basic structure of the Modern Periodic Table is based on the electronic configuration of atoms of different elements?

OR


The electronic configuration of an element is 2,8,4. State its:


(a) Group and period in the Modern Periodic Table.


(b) Name and write its one physical property.


 4

Write two different ways in which glucose is oxidized to provide energy in human body. Write the products formed in each case.

 6

2 g of silver chloride is taken in a china dish and the china dish is placed in sunlight for some time. What will be your observation in this case? Write the chemical reaction involved in the form of a balanced chemical equation. Identify the type of chemical reaction.

OR


Identify the type of reactions taking place in each of the following cases and write the balanced chemical equation for the reactions.


(a) Zinc reacts with silver nitrate to produce zinc nitrate and silver metal


(b) Potassium iodide reacts with lead nitrate to produce potassium and lead iodide.


 7

Identify the acid and base from which sodium chloride is obtained. Which type of salt is it? When is it called rock salt? How is rock salt formed?