24. (a) Write the formula of the sulphate of the element with number 13.   25. (b) What type of bonding will be present in the oxide of the element with atomic number 13.   26. (c) Which feature of the atomic structure accounts for the similarities in the chemical properties of the elements in group 7A of the periodic table?   27. (d) Name the element which has the highest ionization potential.   28. (e) How many electrons are present in the valency shell of the element with the atomic number 18?   29. (f) What is the name given to the energy released when an atom in its isolated gaseous state accepts an electron to form an anion?   30. (g) What is the electronic configuration of the element in the third period which gains one electron to change into an anion?   31. (h) Fill in the blanks: The atomic size ............ as we move from left to right across the period, because the ............... increases but the ........... remains the same.