Question

consider a substance that is present in a sealed container in its solid state at a temperature well below its melting point. over the course of about 15 minutes, the container is heated. at first, the application of heat causes the temperature of the substance to increase until it reaches its melting point temperature. at its melting point temperature, heat is continually added, causing the solid to transition to a liquid at a constant temperature. once all the solid has melted, the substance is heated to its boiling point temperature. at its boiling point temperature, the addition of heat causes the liquid to transition to a gas at a constant temperature. once all the liquid has boiled, the sample continues to be heated (cautiously), causing the temperature of the gas to increase. this process is depicted in figure 1.

figure 1

read the passage to help you answer the questions!!

in this graph, the substance initially starts out as a

at point a, the temperature of the substance is

at point b, the temperature of the substance is during this time, the substance changes from a

at point c, the temperature of the substance is

at point d, the temperature of the substance is during this time, the substance changes from a

at point e, the temperature of the substance is

Explanation:

Step1: Analyze the initial state

The passage states the substance starts in a sealed container in its solid state at a temperature well below its melting point. So the initial state is solid.

Step2: Analyze Point A

Looking at the graph, at time 0 (start) and moving to point A, the temperature is increasing from the initial (below melting point) but still in solid phase. The y - axis (temperature) at point A: from the graph, the initial temperature is - 100°C (assuming the bottom of the y - axis is - 100°C) and point A is at some temperature above - 100 but below the melting point. Wait, no, the passage says "at a temperature well below its melting point" initially. Then heating starts. The first part of the graph (from 0 to around 150 sec maybe) is the solid being heated. So at point A, the temperature is below the melting point, so the substance is solid, and the temperature value: looking at the y - axis, the first horizontal line (melting point) is at, say, 0°C? Wait, the graph has temperature on y - axis with - 100 at the bottom, then 0, then 100, 200, 300. Wait, the passage says "at a temperature well below its melting point" initially. So the initial temperature is below melting point. Then when heating, first the solid's temperature rises until melting point. So point A: temperature is between - 100 and the melting point (the first horizontal segment is melting, so melting point is at the y - value of the first horizontal line). Let's assume the first horizontal line (melting) is at 0°C? Wait, no, the graph's y - axis: the bottom is - 100, then a grid line at 0, then 100, etc. So point A: temperature is, say, - 50°C (approx, from the graph's grid). But the key is the state: solid, temperature below melting point.

Step3: Analyze Point B

Point B is on the first horizontal segment. The passage says "at its melting point temperature, heat is continually added, causing the solid to transition to a liquid at a constant temperature". So the first horizontal line is the melting point. So at point B, temperature is constant (melting point), and the substance is changing from solid to liquid (melting).

Step4: Analyze Point C

After the first horizontal segment (melting) is done, the substance is liquid and being heated. So point C is on the rising part after melting, so temperature is above melting point, below boiling point, substance is liquid.

Step5: Analyze Point D

Point D is on the second horizontal segment. The passage says "at its boiling point temperature, the addition of heat causes the liquid to transition to a gas at a constant temperature". So the second horizontal segment is boiling, so temperature is boiling point, substance is changing from liquid to gas (boiling).

Step6: Analyze Point E

After the second horizontal segment (boiling) is done, the substance is gas and being heated, so temperature is above boiling point, substance is gas.

Answer:

1. In this graph, the substance initially starts out as a \boxed{solid}
2. At point A, the temperature of the substance is (assuming from the graph, if the melting point is 0°C, but maybe the first horizontal line is at 0°C) \boxed{-50^\circ C} (or whatever the correct value from the graph, but based on the passage, it's below melting point) and the substance is \boxed{solid}
3. At point B, the temperature of the substance is \boxed{0^\circ C} (melting point) During this time, the substance changes from a \boxed{solid} to \boxed{liquid} (melting)
4. At point C, the temperature of the substance is \boxed{100^\circ C} (assuming, but actually, after melting, the liquid is heated, so temperature above melting point, below boiling point) and the substance is \boxed{liquid}
5. At point D, the temperature of the substance is \boxed{200^\circ C} (boiling point) During this time, the substance changes from a \boxed{liquid} to \boxed{gas} (boiling)
6. At point E, the temperature of the substance is \boxed{300^\circ C} (above boiling point) and the substance is \boxed{gas}

(Note: The actual temperature values depend on the graph's grid. The key is the state changes: solid -> liquid (melting at constant temp), liquid -> gas (boiling at constant temp), and heating of solid, liquid, gas in between.)