State true or false. The minimum number of carbon atoms in a ketone molecule is two. (1) 5. How does the number of valence electrons vary on moving from left to right in a period? (1) 6. The horizontal rows in a periodic table are called as (1) 7. Name the property of carbon element responsible for a large number of compounds having carbon. (1) 8. On what basis did Mendeleev arrange the elements in his periodic table? On what basis are they arranged now? (2) 9. Three elements A,B & C have electronic configurations (2,7) ; (2,8,1) & (2,8,7).
Which pairs of elements belong to the same group. Which of these is a metal. (2) 10. Five elements A,B, C, D & E have atomic numbers 2,9,11,12 &20. respectively. (i) Which pair of elements are in the same period? (ii) Which of these belong to same period? (2) 11. State two characteristics of homologous series . (2) 12. State any two changes in the properties of I group elements of modern periodic table, if we move downwards. (2) 13. How does metallic character varies in a group and a period? (2) 14. What are structural isomers? Write two structural isomers of butane.
