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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