Answer
$\frac{1}{10^{12}}$
Work Step by Step
Now, $1$ $hr=$ $3.6\times 10^{5}$ $picoseconds$
But $1$ $hr =$ $60$ $minutes=$ $60\times60$ $seconds=$ $3600$ $seconds$
Hence, $1$ $second=$ $\frac{3.6\times10^{15}}{3600}$ $picoseconds=$ $\frac{10^{15}}{10^{3}}$ $picoseconds=$ $10^{15-3}$ $picoseconds=$ $10^{12}$ $picoseconds$
(since $\frac{a^{m}}{a^{n}}=$ $a^{m-n}$)
Thus, $1$ $picosecond=$ $\frac{1}{10^{12}}$ $seconds$
