Question

PLEASE HELP! ASAP! An unknown substance is heated from 10 °C to 25 °C. The table below shows the state of the substance at different temperatures.
Time (minutes) Temperature (degrees Celsius) State of matter
0 10 Liquid
2 15 Liquid
4 20
6 20
8 20
10 23 Gas
12 25 Gas


Which statement is correct about the unknown substance?
Its boiling point is 20 °C.
Its boiling point is 15 °C.
The substance sublimes at 15 °C.
The substance exists as a solid at 20 °C.

Answer 1

Answer: Answer is A) It's boiling point is 20 degree C.

Explanation: Boiling point is the temperature at which a liquid starts boiling and converting into gas.

Looking at the given data, The substance is a liquid at 0 degree C and after heating for 2 minutes its still liquid, On further heating for next 6 minutes(total 8 minutes from starting) the temperature remains constant that indicates a phase change. Since, the substance was initially a liquid, so at 20 degree C the boiling starts and it turns into a gas.

Further heating increases the temperature but the phase does not change and hence its a gas beyond 20 degree C like at 23 degree C and 25 degree C.

So, the right answer is A) It's boiling point is 20 degree C.

Answer 2

It should be 18 but that's not an answer........?