Which is not a common property of ionic compounds

Low melting points and electrical conductivity in solids are not common properties of ionic solids.

Explanation:

In ionic compounds the electrons involved in the bonding are tightly packed under the influence of electrostatic force of attraction. So the movement of these electrons is very difficult.

In the melting point the bond breaking between the atoms is involved. Hence in case of ionic compound there is a high amount of energy needed to break the ionic bonds

property of ionic cpd are: they have high melting point and boiling point, they are solid at room temp

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.