Half-life time of a reaction is time at which reactant concentration becomes half of its initial value.
Half-life of the first order reaction is 20 min. Rate constant can be calculated as follows:
The rate expression for first order reaction is as follows:
initial number of molecules of reactant are 
, time is 100 min thus, putting the values to calculate number of reactant at time 100 min,
![0.03466 min^{-1}=\frac{2.303}{100 min}log\frac{[10^{20}]}{A_{t}}](https://tex.z-dn.net/?f=0.03466%20min%5E%7B-1%7D%3D%5Cfrac%7B2.303%7D%7B100%20min%7Dlog%5Cfrac%7B%5B10%5E%7B20%7D%5D%7D%7BA_%7Bt%7D%7D)
On rearranging,
Or,
Therefore, number of molecules unreacted will be 
Explanation:
A guitar string vibrates when we strikes it. It starts vibrating in several modes simultaneously. It stretches between the saddle and the nut. This distance represents one-half wavelength.
Now if we consider that the string forms a circle, then we have an interpretation of an electron which vibrates in the orbit surrounding the nucleus. We are aware that electrons have wavelength. If the circumference of the orbit happens to be the integer multiple of wavelength
, then the orbit is "allowed" since "the electron will retraces its own path."
This explains the line spectrum and not a continuous spectrum.
A line spectrum refers an electron that jumps between the specific energy levels, thus producing only specific colors.
Something that can not be undone. Like baking bread..cant be undone.
The energy can be shown as:
Q = ms dT
Whereas, m is the mass of block
s is specific heat
dT is change in temperature.
Copper block having the lowest specific heat and thus having the higher change in temperature and therefore having the higher final temperature.
