Answer:
It will take 58 seconds
Explanation:
If you have 1 kg of water in the jar, half of it will be 0.5 kg.
To vaporize half of the water (0.500 kg) the energy supply needed is
![2297 kJ/kg*0.5kg=1148.5 kJ](https://img.qammunity.org/2020/formulas/mathematics/college/nfnoims0ewqrthw9c30lwqpjevuih3njbi.png)
If the stove is supplying 20 kJ/s, the time its needed is
![(1148.5 kJ)/(20(KJ)/(s) )=57.425 s](https://img.qammunity.org/2020/formulas/mathematics/college/e1nwxvqy5fiudtoo592xpvkwilvmno1w84.png)
It will last at least 58 seconds to vaporize half of the water.