Answer:
V₂ = 2.1 L 
Step-by-step explanation:
Given data:
Initial volume of balloon = 2.0 L
Initial temperature = 25°C
Final temperature = 35°C
Final volume of balloon in hot room = ?
Solution:
Initial temperature = 25°C (25+273= 298 K)
Final temperature = 35°C (35+273 = 308 k)
According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure. 
Mathematical expression: 
V₁/T₁ = V₂/T₂ 
V₁ = Initial volume 
T₁ = Initial temperature 
V₂ = Final volume 
T₂ = Final temperature 
Now we will put the values in formula. 
V₁/T₁ = V₂/T₂ 
V₂ = V₁T₂/T₁ 
V₂ = 2.0 L × 308 K / 298 k 
V₂ = 616 L.K / 298 K 
V₂ = 2.1 L