Identify the carrier gas commonly used in gas chromatography.

Perform the following calculations for the given exponential numbers:
$(i)$ $(6.7 \times 10^4) \times (8.4 \times 10^7)$
$(ii)$ $\frac{(3.4 \times 10^{-3})}{(6.5 \times 10^{-7})}$

Which of the following has the highest energy value?

The unit $J \, Pa^{-1}$ is equivalent to

The number of significant figures in $2.0400$ is

$3.00 \ kg$ is equal to how many yards? Given: $1 \ kg = 1000 \ m$,$1 \ m = 1.094 \ yards$.