Question

2

The table gives the melting and boiling points of four pure substances, W, X, Y and Z.
Melting point in °C
Boiling point in °C
w
-7
60
Х
660
2500
Y
180
1330
Z
115
445
Use data from the table to answer the questions.
(a) (0) Which substance is a gas at 100°C?
X AW
B X
D CY
DZ
(ii) Which substance is a liquid for the largest range of temperature?
D A W
B X
CY
DZ
liquid at 1000 °C and a gas at 2000°C?​

Answer 1

(a) W

(b) X

(c) Y

Step-by-step explanation:

Let's consider the following table with melting and boiling points for 4 substances.

Substance Melting Point (°C) Boiling Point (°C)

W -7 60

X 660 2500

Y 180 1330

Z 115 445

Let's consider that:

• Below the melting point, a substance is solid.
• Between the melting and the boiling point, a substance is liquid.
• Above the boiling point, a substance is gas.

(a) Which substance is a gas at 100°C?

At 100 °C, W is above the boiling point

(b) Which substance is a liquid for the largest range of temperature?

The largest difference between the melting point and the boiling point is that of X: 2500 - 660 = 1840.

(c) Which substance is liquid at 1000 °C and a gas at 2000°C?​

Y is between the melting and the boiling point at 1000 °C and above the boiling point at 2000 °C.