Answer:

Explanation:
Mass of the helium gas filled inside the volume of balloon is given as




now total mass of balloon + helium inside balloon is given as


now we know that total weight of balloon + cargo = buoyancy force on the balloon
so we will have




Here in nuclear reaction we can say that sum of neutrons and protons in reactant side and product side will be same always
Here mass number on the product side is given to us
so sum of mass number is given as

now on the reactant side also the number must be same

now we will have


Now number of protons on product side is given as

now we also know that atomic number of Fe is 26
so now we will have



now the equation is given as

From the concept of optics on a curvature of a spherical mirror, the proportion for which the focal length is equivalent to half the radius of curvature is fulfilled. Mathematically this is

Here,
f = Focal Length
R = Radius
Rearranging to find the radius we have,

Replacing with our values,
R = 2(13.8cm)
R = 27.6cm
Therefore the radius of the spherical surface from which the mirror was made is 27.6cm
<span>Heat is radiated, atmospheric moisture condenses at a rate greater than that at which it can evaporate, resulting in the formation of water droplets.</span>