All the boron trihalides exceptBI_(3) may be prepared by direction between the elements. Boron trihalides consist of trigonal-planar BX_(3) molecules. Unlike the halides of the other elements in the group they are monomeric in the gas, liquid and solid states, BF_(3) and BCl_(3) are gases, BBr_(3) is a volatile liquid and BI_(3) is a solid. Boron trihalides are Lewis acids because they form simple Lewis complexes with suitable bases, as in the reaction: BF_(3)(g)+NH_(3)(g)toF_(3)B-NH_(3)(s) However, boron chlorides, bromides and iodides are susceptible (sensitive) to protolysis by mild proton sources such as water, alcohols and even amines, for example BCl_(3) undergoes rapid hydrolysis: BCl_(3)(g)+3H_(2)O(l)toB(OH)_(3)(aq)+3HCl (aq)It is supposed that the first step in the above reaction is the formation of the complex Cl_(3)B larr OH_(2) which then eliminates HCl and reacts with water. Which of the following is the correct prediction about observed B-X bond length, in BX_(3) molecules?