The answer is mass. I have to comment more than 20 characters.
A=atomic mass
Z=atomic number (nº of protons).
N=neutons.
A=Z+N
Data:
A=39
Z=19
A=Z+N
39=19+N
N=39-19=20.
It therefore has 20 neutrons in its nucleus.
Answer:
Explanation:
Given
mass of tin 
Also we know that
specific heat of tin 
Melting Point of Tin 
Heat required to raise the temperature of 100 gm tin is given by

where 




Answer:
To find the diameter of the wire, when the following are given:
Resistivity of the material (Rho), Current flowing in the conductor, I, Potential difference across the conductor ends, V, and length of the wire/conductor, L.
Using the ohm's law,
Resistance R = (rho*L)/A
R = V/I.
Crossectional area of the wire A = π*square of radius
Radius = sqrt(A/π)
Diameter = Radius/2 = [sqrt(A/π)]
Making A the subject of the formular
A = (rho* L* I)V.
From the result of A, Diameter can be determined using
Diameter = [sqrt(A/π)]/2. π is a constant with the value 22/7
Explanation:
Error and uncertainty can be measured varying the value of the parameters used and calculating different values of the diameters. Compare the values using standard deviation