The higher oxide formula corresponds to the element number R2O5: A) 15; B) 11; C) 14; D) 34

In the higher oxide, the element exhibits its highest valence, which is equal to the group number. If the formula of the higher oxide is R2O5, then the valence of the element in it is 5, which means that we need to look for an element of group 5 of the periodic table of elements.

A) No. 15 – P (phosphorus), located in group 5;

B) No. 11 – Na (sodium), located in group 1;

B) No. 14 – Si (silicon), located in group 4;

D) No. 34 – Se (selenium), located in the 6th group.