How does the energy required to sublime a substance compare to the energy required to melt the substance

The energy required to sublime (solid to gas) a substance at 1 ATM pressure is greater than the energy required to melt (solid to liquid) a substance. When you compare the energies in varying pressures, however, this trend is not always the case. 

any 'general phase diagram', you can see that under the triple point, when all phases are in equilibrium, have solid and gas meeting under a certain pressure. In a vacuum, it would require less energy to sublime than to melt.

The answer is false because: gravitational force is independent of medium and depends only on the masses of the two objects and the distance between them

    pb(so₄)₂this element is lead (iv) sulfate. lead is a multivalent ion. but we know that sulfate ions, so₄²⁻, have a charge of -2. in order to have the ratios match up, we need pb⁴⁺ (two times as many pb⁴⁺  than so₄²⁻).the molar mass can be calculated by finding the mass of one mole of this compound. consider the following calculation,  where amu represents the atomic mass unit. the amu for each atom involved in this compound can be found on a periodic table.  molar mass = amu pb + 2(amu s + 4 * amu o)from a periodic table (with masses rounded to the nearest tenth),      amu pb = 207.2 g    amu s =  32.1 g    amu o = 16.0 gtherefore    molar mass =  207.2 + 2(32.1 + 4*16.0) = 399.4 gthe molar mass is therefore 399.4 grams per mol