The sodium in soda lowers the melting point and makes the ice melt more slowly than it would in plain water because with the addition of any substance, there are fewer free water molecules available to form bonds together and freeze
The balloon's volume at 35°C : V₂=31.01 L
<h3>Further explanation</h3>
Given
T₁ = 25°C+273 = 298 K
V₁ = 30 L
T₂ = 35 °C + 273 = 308 K
Required
The new volume (V₂)
Solution
Charles's Law
When the gas pressure is kept constant, the gas volume is proportional to the temperature

Input the value :
V₂=(V₁.T₂)/T₁
V₂=(30 x 308)/298
V₂=31.01 L