True.
Conductivity is the ability to transmit heat, electricity or sound. Conductivity is a physical property.
A physical property is one which can be measured or observed without changing the composition or identity of a the substance.
Conductivity is a physical property because the composition of the substance does not change.
A copper wire is still a copper wire when it is conducting electricity. Like wise, an aluminum rod is still an aluminum rod when heated. It is conducting heat but the heat does not change it, it is still an aluminum rod during the whole process.
Note: I'm not sure what do you mean by "weight 0.05 kg/L". I assume it means the mass per unit of length, so it should be "0.05 kg/m".
Solution:
The fundamental frequency in a standing wave is given by

where L is the length of the string, T the tension and m its mass. If we plug the data of the problem into the equation, we find

The wavelength of the standing wave is instead twice the length of the string:

So the speed of the wave is

And the time the pulse takes to reach the shop is the distance covered divided by the speed:
<h2>
Answer: The half-life of beryllium-15 is 400 times greater than the half-life of beryllium-13.</h2>
Explanation:
The half-life
of a radioactive isotope refers to its decay period, which is the average lifetime of an atom before it disintegrates.
In this case, we are given the half life of two elements:
beryllium-13: 
beryllium-15: 
As we can see, the half-life of beryllium-15 is greater than the half-life of beryllium-13, but how great?
We can find it out by the following expression:

Where
is the amount we want to find:


Finally:

Therefore:
The half-life of beryllium-15 is <u>400 times greater than</u> the half-life of beryllium-13.
Explanation:
In the given situation two forces are working. These are:
1) Electric force (acting in the downward direction) = qE
2) weight (acting in the downward direction) = mg
Therefore, work done by all the forces = change in kinetic energy
Hence,
It is known that the weight of electron is far less compared to electric force. Therefore, we can neglect the weight and the above equation will be as follows.

v = 
= 592999 m/s
Since, the electron is travelling downwards it means that it looses the potential energy.
Using the formula KE=1/2mv^2
a: The kinetic energy doubles.
b: The kinetic energy quadruples.
c: The kinetic energy is cut in half.
Hopefully it’s clear how the formula can show you this.