Question

( PLEASE HELP ASAP! BIG POINTS! ) An unknown substance is heated from 10 °C to 25 °C. The table below shows the state of the substance at different temperatures.


First row: Time
(minutes)

Second row: Temperature of liquid
(degrees Celsius)

Third row: State of matter

0 10 Solid
2 15 Solid
4 17
6 17
8 17
10 23 Liquid
12 25 Liquid


Which statement is correct about the unknown substance?
A. Its melting point is 17 °C.
B. Its melting point is 15 °C.
C. The substance sublimes at 15 °C.
D. The substance exists as a gas at 17 °C.

Answer 1

Answer: Option (A) is the correct answer.

Explanation:

It is given that the unknown substance is solid at 15 degree celsius. When further heated then heat energy breaks the bond between molecules of the solid.

As a result, temperature remains constant until all the bonds are broken down to convert the solid into liquid.

Hence, the constant 17 degree celsius temperature shows that the solid is melting and after it completely melts then it converts into liquid at 23 degree celsius.

Thus, we can conclude that the statement its melting point is 17 °C, is correct about the unknown substance.

Answer 2

The correct answer is A. 17 degrees Celsius

The reason why is because the temperature in degrees Celsius for it to turn into a solid is 23 degrees and it isn't quite 23 degrees but not so little it will barely do anything to it at all.