Answer: The order of increasing lattice energy is 
Explanation: Lattice energy is defined as the energy required to break the intermolecular force that is responsible for the formation of a lattice.
Melting point is defined as the temperature at which solid gets converted into liquid due to the weakening of the bonds in the solid form.
- Relation between lattice energy and Melting point:
The relationship between these two is direct.

More the melting point of a compound, more will be its lattice energy.
Order of increasing Lattice energy will be:

They're totally unrelated. No matter how low or high the molecular weight, you can always use more or less of it.
Answer:
being polar, it can easily dissolve other polar substances or substances with ionic bonds like nacl
Answer:
isotopes
Atoms with the same number of protons but different numbers of neutrons are called isotopes. Because the number of neutrons can vary for a given element, the mass numbers of different atoms of an element may also vary. For example, some helium atoms have three neutrons instead of two (these are called isotopes and are discussed in detail later on)
Explanation: