The density of neon will be highest at

The density of air is higher at sea level. Which of the following laws explains this practical observation?

Equal volumes of two gases which do not react together are enclosed in separate vessels. Their pressures are $100 \ mm$ and $400 \ mm$ respectively. If the two vessels are joined together,then what will be the pressure of the resulting mixture (temperature remaining constant)?

On a ship sailing in the Pacific Ocean where the temperature is $23.4^{\circ} C$,a balloon is filled with $2 \ L$ of air. What will be the volume of the balloon when the ship reaches the Indian Ocean,where the temperature is $26.1^{\circ} C$ (in $L$)?

In a closed vessel of volume $0.082 \, dm^3$ at $600 \, K$,the complete decomposition of methanol vapor occurs as follows: $CH_3OH_{(g)} \to CO_{(g)} + 2H_{2(g)}$. If $0.01 \, mol$ of methanol is taken initially,what will be the pressure generated in the vessel in $atm$?

The molecular weights of $O_2$ and $SO_2$ are $32$ and $64$ respectively. If $1 \, L$ of $O_2$ at $15 \, ^\circ C$ and $750 \, mm$ pressure contains '$N$' molecules,the number of molecules in $2 \, L$ of $SO_2$ under the same conditions of temperature and pressure will be