The molecule BH3 is trigonal planar, with B in the center and H in the three vertices. Ther are no free electrons. All the valence electrons are paired in and forming bonds.
There are four kind of intermolecular attractions: ionic, hydrogen bonds, polar and dispersion forces.
B and H have very similar electronegativities, Boron's electronegativity is 2.0 and Hydrogen's electronegativity is 2.0.
The basis of ionic compounds are ions and the basis of polar compounds are dipoles.
The very similar electronegativities means that B and H will not form either ions or dipoles. So, that discards the possibility of finding ionic or polar interactions.
Regarding, hydrogen bonds, that only happens when hydrogen bonds to O, N or F atoms. This is not the case, so you are sure that there are not hydrogen bonds.
When this is the case, the only intermolecular force is dispersion interaction, which present in all molecules.
Then, the answer is dispersion interaction.
Answer:
it will probably flame up or explode or maybe start boiling
If a substance is not chemically pure, it is either a heterogeneous mixture or a homogeneous mixture. If its composition is uniform throughout, it is a homogeneous mixture.
Molar mass can be determined by adding the atomic masses of each individual element, depending on how many times they appear. You can find how many times they appear by looking at their respective subscripts. Atomic masses of each element can be found on the periodic table.
For example, in #1
Multiply the mass of Lithium (6.941) by 4, because there are 4 lithium molecules.
Multiple the mass of Phosphorus (30.974) by 2 because there are 2 Phosphorus molecules.
And multiply the mass of oxygen (15.999) by 7 because there are 7 oxygen molecules.
After you have those values, add them together to find the total molar mass of the compound.