It’s True the volume is 1k of iron is = 1
A, Mechanical and A, Chemical.
Answer:

Explanation:
We have given initial length of the steel guitar l = 1 m
Cross sectional area 
Young's modulus 
Force F = 1500 N
So stress 
We know that young's modulus 
So 

Now strain 


Answer:
4.14 eV
Explanation:
f = 1.0 ×10^15 Hz
h= 6.63×10^-34 J s ( this is called PLANCK 'S CONSTANT)
ENEGY = E = ?
E = hf ( THIS IS FORMULA FOR ENERGY OF ONE QUANTA OR ONE PHOTON )
E= 6.63×10^-34×1.0 ×10^15
E = 6.63×10^-19 J
As 1eV = 1.6×10^-19 J so changing energy in eV from joules we will divide energy by 1.6×10^-19
hence E in eV = 6.63×10^-19/(1.6×10^-19)
E = 4.14 eV