Mass number = protons + neutrons = 34+46 =80
the element with an atomic number of 34 and mass number of 80 is selenium
The percent by mass sugar of a solution : 11.07%
<h3>Further explanation</h3>
Given
mass of sugar = 12.45 g
mass of water = 100 g
Required
The percent by mass
Solution
Mass of solution :

Percent mass of sugar :

Answer: the molecular formula is C10H20O
Explanation:Please see attachment for explanation