Find the number of electrons that generate $1$ coulomb charge?

State whether the following statements are true or false:
$(i)$ The Law of Multiple Proportions was given by the scientist Dalton.
$(ii)$ $1 \ L = 1 \ dm^3$
$(iii)$ $10 \ cm = 1 \ dm$

Define density and provide its $SI$ unit.

$1 \, kg \, m^{-3} = \dots \, g \, cm^{-3}$

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

Choose the correct statements.
$A$. Weight of a substance is the amount of matter present in it.
$B$. Mass is the force exerted by gravity on an object.
$C$. Volume is the amount of space occupied by a substance.
$D$. Temperatures below $0^{\circ} C$ are possible in Celsius scale,but in Kelvin scale negative temperature is not possible.
$E$. Precision refers to the closeness of various measurements for the same quantity.