| The position of eight elements in the Modern Periodic Table is given below where atomic numbers of elements are given in the parenthesis. | ||
| Period No. | ||
| 2 | Li (3) | Be (4) |
| 3 | Na (11) | Mg (12) |
| 4 | K (19) | Ca (20) |
| 5 | Rb (37) | Sr (38) |
| (i) Write the electronic configuration of Ca. | ||
| (ii) Predict the number of valence electrons in Rb. | ||
| (iii) What is the number of shells in Sr? | ||
| (iv) Predict whether K is a metal or a non-metal. | ||
| (v) Which one of these elements has the largest atom in size? | ||
| (vi) Arrange Be, Ca, Mg and Rb in the increasing order of the size of their respective atoms. | ||
| An element 'X' belong to 3rd period and group 13 of the Modern Periodic Table. |
| (a) Determine the valence electrons and the valency of 'X'. |
| (b) Molecular formula of the compound formed when 'X' reacts with an element 'Y' (atomic number = 8). |
| (c) Write the name and formula of the compound formed when 'X' combines with chlorine. |
| (a) Define focal length of a divergent lens. |
| (b) A divergent lens of focal length 30 cm forms the image of an object of size 6 cm on the same side as the object at a distance of 15 cm from its optical centre. Use lens formula to determine the distance of the object from the lens and the size of the image formed. |
| (c) Draw a ray diagram to show the formation of image in the above situation. |
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