Answer:

Explanation:
For a linear elastic material Young's modulus is a constant that is given by:

Here, F is the force exerted on an object under tensio, A is the area of the cross-section perpendicular to the applied force,
is the amount by which the length of the object changes and
is the original length of the object. In this case the force is the weight of the mass:

Replacing the given values in Young's modulus formula:

so the 1st on is the one on the left, middle is right and the 3rd one is the right one
Answer: 
Explanation:
The angular diameter
of a spherical object is given by the following formula:

Where:
is the actual diameter
is the distance to the spherical object
Hence:

This is the angular diameter
The answer is C. an electron in an orbit has a fixed energy.
Comparative investigation is a research method that makes comparison across different countries of the world. Limitation : data set in different countries may be defined differently. Benefit : the method is flexible.