The new temperature of the gas inside the balloon : 609 °C
Further explanation
Charles's Law
When the gas pressure is kept constant, the gas volume is proportional to the temperature
[tex]\tt \dfrac{V_1}{T_1}=\dfrac{V_2}{T_2}[/tex]
The balloon is heated, causing it to expand (pressure constant) :
V₁=1.9 L
T=21+273=294 K
V₂=5.7 L
[tex]\tt T_2=\dfrac{T_1\times V_2}{V_1}\\\\T_2=\dfrac{294\times 5.7}{1.9}\\\\T_2=882 K=609 ^oC[/tex]
