Three substances a, b, and c melt at 00c,500c and -1500c respectively and their boiling points are 1000c , 2000c and 100c. state the physical nature of a, b and c at room temperature

That information is better presented and analyzed in a table.

This table shows you all the information and the answers:

Substance         melting point   boiling point    room temperature    conclusion
                                    °C                  °C                      °C                    (state)

A                                  0                    100                    25                    liquid

B                                  50                  200                    25                    solid
C                               -150                   10                     25                    gas

Explanation:

1) Substance A at 25° is above the melting point and below the boiling point, then it is liquid (just like water)

2) Substance B at 25°C is below the melting point, so it is solid.

3) Substance C at 25°C is above the boiling point, so it is gas.

1.from liquid state to gaseous state is evaporation 3.solid to liquid is melting 5. solid to gaseous state is sublimation 6. gas to solid state is decomposition 7. a change of state is known as the states of matters

Answer is to avoid experimental error