if the size of nucleus (1x10^-15m) is scaled upto the tip of a sharp pin (1x10^-5m) what roughly is the size of the atom.?

Simply multiply by a factor of 10^10 so the nucleus is now 1E-5 m. And that's the size of the core; but the first electrons pop in and out about 10,000 times farther out. So the whole atom, including the first S orbital electrons would be roughly 1E-1 meters. A tenth of a meter.

An atom's length scale is on the order of an angstrom or 1x10^-10 m. To get from 1e-15 to 1e-5, you had to multiply by a factor of 1e+10 (1x10^10), and if we do the same thing with 1x10^-10 we get 1.0 m