According to VSEPR theory, the presence of lone pairs caused increased repulsion of electron pairs on the valence shell of the centeral atom of the molecule. This decreases or distorts the bond angle. The decrease in bond ange depends on the number of lone pairs present on the valence shell of the central atom of the molecule. Ammonia has only one lone pair hence the bond angle is 107°, water has two lone pairs and the bond angle is 104°. Compare this this with the bond angle of 109° in methane which has only bond pairs and no lone pairs.
It is true that substances that have a high melting point and conduct electricity in the liquid phase are ionic substances, and if one of your options is NaCl, then that is the correct answer.
Here is a drawing of butane (C4H10); labeled #1. An isomer of butane will also have the chemical formula C4H10 but is depicted different geometrically. I labeled this one #2.
