There is an element that can be compared with B O N

Assuming that the element is r, since there should be at least one b, n, and o in the formed compound, it is assumed that there is a b, an n, and an o respectively, and the molecular mass of the possible compound can be calculated: the molecular mass of the compound formed with b = 11, the molecular mass of the compound formed with n = 14, and the molecular mass of the compound formed with o = 16, because they are all greater than 50, it can be seen that there can only be one bno in the compound formed by r and bno.

Regardless of whether R is a metal or a non-metal, O is plus or minus 2 valence, N is plus or minus trivalent, and R can only be plus or minus 1 valence in the formed compound, otherwise the formed compound cannot be an O or N, for example, if R is 2 valence, then O is just 1:1, but N will be 2:3.

From this, the compound can be br3nr3or2, which can be calculated arbitrarily, for example, br3 has 11+3r=68, r=19, which is fluorine element f.

The three compounds are BF3, NF3, OF2

Fluorine. bf3、nf3、of2

First of all, this substance cannot be a metal, because there is no metal that forms a compound with B, so it must be a non-metal, let its valency be -1, expressed by R, and the molecular weight is R, then the compound formed is Br3, Nr3. Then use the values of b% and n% to calculate r, and find that r=19, so it is f, obviously f can form compound of2 with o, and it has been verified that o% is determined in.

The first ionization energy of an element of the same main group.

With atomic number.

The first ionization energy of the element in the same period increases with the increase of the atomic number, note that the first ionization energy of element a in the same period is greater than that of group a, and the energy of group a is greater than that of group a

A f, o, n belong to the same periodic elements and the atomic number decreases in turn, the first ionization energy of the same periodic element increases with the increase of atomic number, but the first ionization energy of group a is greater than that of group a, so the order of the first ionization energy is f, n, o, so a is wrong;

b Na, Mg, Al belong to the same periodic elements and the atomic number increases in turn, and their first ionization energy increases with the increase of atomic number, but the first ionization energy of element a is greater than that of group a, so the order of the first ionization energy is mg, al, na, so b is wrong;

c i, br and cl belong to the same main group element and the atomic number decreases according to the disturbance order, and the first ionization energy of the same main group element decreases with the increase of atomic number, so its first ionization energy increases sequentially, so c is wrong;

d h, li, na belong to the same main group of elements and the atomic number increases sequentially, and their first ionization energy decreases with the increase of atomic number, so their first ionization energy decreases sequentially, so d is correct

Therefore, choose D