The compound sodium iodide is a strong electrolyte. Write the reaction when solid sodium iodide is put into water.

NaI(s) → Na⁺(aq) + I⁻(aq)

Explanation:

The chemical formula of sodium iodide is NaI. When NaI is dissolved in water, it dissociates into sodium ions (Na⁺) and iodide ions (I⁻). One mol of NaI gives 1 mol of Na⁺ ions and 1 mol of I⁻ ions.

Therefore, the chemical equation for the dissociation is the following:

NaI(s) → Na⁺(aq) + I⁻(aq)

there are two significant figures.

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.