Solution :
Acidic character of oxide Non-metallic nature of element.
Non-metallic character increases along the period. Hence order of acidic character is
$$C{l_2}{O_7} > S{O_2} > {P_4}{O_{10}}.$$
Releted MCQ Question on Inorganic Chemistry >> Classification of Elements and Periodicity in Properties
Releted Question 1
The correct order of second ionisation potential of carbon, nitrogen, oxygen and fluorine is