# Pls tell sol for 5,6,7

The solution/s to your 1st query (Q5) has been provided below:

Q5.

Given,

the distance of the nearest star, Proxima Centauri from the earth is $d=4.0\times {10}^{13}km$.

1 light year is the distance travelled by light in 1 year.

Thus,

$1lightyear=c\times t=3\times {10}^{8}\frac{m}{s}\times 1year=3\times {10}^{8}\frac{m}{s}\times 1year\times 365\frac{days}{year}\times 24\frac{hours}{day}\times 3600\frac{sec}{hour}=94608000\times {10}^{8}m.\phantom{\rule{0ex}{0ex}}Thus,\phantom{\rule{0ex}{0ex}}d=4.0\times {10}^{16}m=\frac{4.0\times {10}^{16}m}{94608000\times {10}^{8}{\displaystyle \raisebox{1ex}{$m$}\!\left/ \!\raisebox{-1ex}{$lightyear$}\right.}}=4.227lightyear\approx 4.2lightyear$

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