Chapter 1, Problem 65A

a)

Interpretation Introduction

Interpretation : The independent variable and the dependent variable are to be identified.

Concept Introduction : The experiment when constructed usually deals with variables or factors that change.

Answer to Problem 65A

The independent variable is the amount of salt added.

Explanation of Solution

The independent variable is that which can be modified during an experiment. It is also called a manipulated variable.

An independent variable keeps changing during an experiment whereas the dependent variable changes according to the independent variable.

According to the definition, the amount of salt added is the independent variable.

b)

Interpretation Introduction

Interpretation : The factors that should be kept constant during the experiment are to be named.

Concept Introduction : The experiment when constructed usually deals with variables or factors that change.

Answer to Problem 65A

The dependent variable is the freezing point of salt water.

Explanation of Solution

A dependent variable is measured during an experiment. It is also called a responding variable.

An independent variable keeps changing during an experiment whereas the dependent variable changes according to the independent variable.

According to the definition, the freezing point of the salt water is the dependent variable.

c)

Interpretation Introduction

Interpretation : The volume of water should be the same for each test to be explained.

Concept Introduction : The experiment when constructed usually deals with variables or factors that change.

Answer to Problem 65A

To avoid unnecessary confusion and to get accurate results, the volume of the water is kept constant.

Explanation of Solution

The independent variable is the one that can be modified during an experiment. It is also called a manipulated variable.

A dependent variable is measured during an experiment. It is also called a responding variable.

An independent variable keeps changing during an experiment whereas the dependent variable changes according to the independent variable.

The volume of the water should be kept constant for each of the tests. This is because if there is any volume change it also affects the freezing point since the change in volume and salt getting mixed with the volume of water differs.

To avoid unnecessary confusion and to get accurate results, the volume of the water is kept constant.

d)

Interpretation Introduction

Interpretation : The hypothesis supported by the data is to be explained.

Concept Introduction : A hypothesis is a theory put up to explain an observable.

Answer to Problem 65A

The hypothesis supports the answer till 15 g of salt addition.

Explanation of Solution

A hypothesis is a theory put up to explain an observable. Only if it explains what is witnessed is it valuable. The hypothesis must be modified when experimental data does not support it.

Yes, the hypothesis made by the student is correct till 15 g of salt addition. The temperature of freezing decreases as the salt addition is added more and more till 15 g. But after that, there is a slight rise in freezing temperature.

To find the trend, furthermore, salts are to be added and the temperature of freezing should be noted.