Any substance that contains starch turns blue-black in presence of <u>iodine solution.</u>
When red light illuminates a grating with 7000 lines per centimeter, its second maximum is at 62.4°. What is the wavelength of this light?
ans: 633nm
g Generally the accepted value of acceleration due to gravity is 9.801 
as per the question the acceleration due to gravity is found to be 9.42
in an experiment performed.
the difference between the ideal and observed value is 0.381.
hence the error is -
=3.88735 percent
the error is not so high,so it can be accepted.
now we have to know why this occurs-the equation of time period of the simple pendulum is give as-![T=2\pi\sqrt[2]{l/g}](https://tex.z-dn.net/?f=T%3D2%5Cpi%5Csqrt%5B2%5D%7Bl%2Fg%7D)

As the experiment is done under air resistance,so it will affect to the time period.hence the time period will be more which in turn decreases the value of g.
if this experiment is done in a environment of zero air resistance,we will get the value of g which must be approximately equal to 9.801 
Can I see the graph so I can help you
Answer:
The answer is D
Explanation:
I'm too lz to explain everything.
sorry.