At what temperature will the values of $^\circ C$ and $^\circ F$ be equal?

$5 \times 10^2 \, cm = .......... \, dm$

$1 \, \mu g = ........ \, mg$

Select the $INCORRECT$ statement/s from the following:
$(a)$ $22$ books have infinite significant figures
$(b)$ In the answer of calculation $2.5 \times 1.25$,the result has four significant figures.
$(c)$ Zeros preceding the first non-zero digit are significant.
$(d)$ In the answer of calculation $12.11 + 18.0 + 1.012$,the result has three significant figures.

How many seconds are there in $2$ days (in $s$)?

$A$ cuboidal container is filled with $20 \ L$ of water. If the length of the container is $30 \ cm$ and the width is $25 \ cm$,then the height will be ..... $dm$.