Answer:

Explanation:
Range = Highest value - Lowest value
A 'soft solder' melts between 183 °C and 212 °C.
Melting range of a 'soft solder' = 
A 'hard solder' melts between 620 °C and 680 °C.
Melting range of a 'hard solder' = 
So,
Difference in melting ranges = Melting range of a 'hard solder' - Melting range of a 'soft solder' = 
132 cm to 0.00132 km.
there you go, hope this helps!
Then I would guess the answer is D because Na2OH is much more common and stable than Na2O is <span />