The prefix zepto stands for

How many significant figures are present in the following?
$(i)$ $0.0025$
$(ii)$ $208$
$(iii)$ $5005$
$(iv)$ $126.000$
$(v)$ $500.0$
$(vi)$ $2.0034$

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

According to the significant figure convention, the result obtained by adding $12.11$, $18.0$, and $1.012$ is:

Fill in the blanks given below:
$(i)$ The symbol for the quantity of luminous intensity is .......... and the name of its $SI$ unit is ......... .
$(ii)$ The prefixes used for $10^{-18}$ and $10^{18}$ are ............ and ........... respectively.
$(iii)$ The $SI$ unit of density is ......... .
$(iv)$ In the ........ unit of temperature,its negative value is not possible.

From the following masses,the one which is expressed nearest to the milligram is (in $g$)