If the diameter of a carbon atom is $0.15 \,nm$,calculate the number of carbon atoms which can be placed side by side in a straight line across the length of a scale of length $20 \,cm$.

Match the following physical quantities with their appropriate units.

Physical Quantity	Unit
$(A)$ Molarity	$(1)$ $g \ mL^{-1}$
$(B)$ Mole fraction	$(2)$ $mol$
$(C)$ Mole	$(3)$ $Pascal$
$(D)$ Molality	$(4)$ $Unitless$
$(E)$ Pressure	$(5)$ $mol \ L^{-1}$
$(F)$ Luminous intensity	$(6)$ $Candela$
$(G)$ Density	$(7)$ $mol \ kg^{-1}$
$(H)$ Mass	$(8)$ $N \ m^{-1}$
	$(9)$ $kg$

If an object weighs $275 \ lb$,what is its weight in $kg$? $(1 \ kg = 2.205 \ lb)$

The candela is the luminous intensity,in a given direction,of a source that emits monochromatic radiation of frequency '$A$' $\times 10^{12}$ hertz and that has a radiant intensity in that direction of $\frac{1}{B}$ watt per steradian. '$A$' and '$B$' are respectively

The number of significant figures in $0.00051$ is:

Which of the following units represents the largest amount of energy?