Molecules in a sample of nh3(l) are held closely together by intermolecular forces
(1) existing between ions(2) existing between electrons(3) caused by different numbers of neutrons(4) caused by unequal charge distribution

Molecules in a sample of NH3(l) are held closely together by intermolecular forces existing between ions. The answer is number 1. NH3 is governed by hydrogen bonding. Hydrogen bonding is the bonding between an H atom and the element that it combines with.

conduction is the transfer of thermal energy (heat in transfer) due to collisions between the molecules in the object. collisions between adjacent atoms and molecules transfer kinetic energy from the warmer to the cooler object. the objects must be in physical contact.

explanation:

let the different atoms be x and y. each with four protons and same mass will be represented as follows.

mass number is number of protons + number of neutrons.

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since, it is given that one has a negative charge while the other is neutral. therefore, there will be increase in number of protons and the atom will be represented as follows.

according to periodic table, mass number of beryllium is 9 and it has atomic number 4 so, the atoms will be and .  

the protons and neutrons will be located inside the nucleus whereas the electrons will be revolving around the nucleus.