Understanding Mass of a Substance

The question asks about the properties of the mass of a particular amount of substance. Let's analyze each statement provided.

Analysis of Statements about Mass

Statement 1: is the amount of matter present in it.

This is the fundamental definition of mass. Mass is a measure of the inertia of an object, which is directly related to the amount of matter it contains. The more matter, the greater the mass.

• This statement is correct.

Statement 2: does not vary from place to place.

Mass is an intrinsic property of an object. It depends only on the amount and type of matter constituting the object. Unlike weight, which is the force of gravity acting on mass, mass itself is constant regardless of where the object is located – be it on Earth, the Moon, or in space. The gravitational force might change, but the amount of matter does not.

• This statement is correct.

Statement 3: Changes with the change in gravitational force.

This statement is incorrect. Mass is a measure of the amount of matter and its resistance to acceleration (inertia). It does not change with variations in gravitational force. What changes with gravitational force is weight. Weight is given by the formula \( \text{Weight} = \text{Mass} \times \text{Gravitational Acceleration} \). Since gravitational acceleration varies with location, weight changes, but mass remains constant.

• This statement is incorrect.

Evaluating the Options

Based on our analysis:

• Statement 1 is correct.
• Statement 2 is correct.
• Statement 3 is incorrect.

We are looking for the option that includes only the correct statements.

• Option 1: 1, 2 and 3 (Includes incorrect statement 3) - Incorrect.
• Option 2: 1 and 2 only (Includes correct statements 1 and 2) - Correct.
• Option 3: 2 and 3 only (Includes incorrect statement 3) - Incorrect.
• Option 4: 1 only (Misses correct statement 2) - Incorrect.

Therefore, the correct option is the one stating "1 and 2 only".

Revision Table: Properties of Mass

Additional Information: Mass vs. Weight

It is crucial to understand the difference between mass and weight, as they are often confused.

• Mass: This is an intrinsic scalar quantity representing the amount of matter in an object. Its SI unit is the kilogram (kg). Mass is constant regardless of location or gravitational field strength.
• Weight: This is a force, specifically the force exerted by gravity on an object's mass. It is a vector quantity and is calculated as \( \text{Weight} = \text{mass} \times \text{acceleration due to gravity (g)} \). Its SI unit is the Newton (N). Weight varies with the local gravitational acceleration, which changes with altitude, latitude, and the mass of the celestial body. For example, an object has less weight on the Moon than on Earth because the Moon's gravitational acceleration is lower.

In summary, mass is a fundamental property of a substance and remains constant, while weight is a force that depends on both mass and the local gravitational field.