Which of the following statement is not a correct statement about the trends when going from left to right across the periods of Periodic Table?

If we check all options in option (a) it is true that elements become less metallic decreases because tendency to lose e^- decreases, in option (b) this statement is also true that valence electrons increases in option (c) it is not true because tendency to lose electrons is difficult across the period and (d) option is also correct as the oxides become more acidic.

So, the correct answer is an option (c).