Helium is added to the oxygen supply used by deep sea divers because

Which of the following mixtures of gases cannot be used to demonstrate Dalton's Law of Partial Pressures?

$A$ person living in $Manali$ observed that cooking food without using a pressure cooker takes more time. The reason for this observation is that at high altitude:

The units of surface tension and viscosity of liquids respectively are

$A$ person living in $Shimla$ observed that cooking food without using a pressure cooker takes more time. The reason is that at high altitude:

At $T \ K$,equal weights of $H_2, D_2$,and $T_2$ are present in a closed vessel. The pressure exerted by this gaseous mixture is $P \ atm$. The ratio of partial pressures of $T_2, D_2$,and $H_2$ is approximately. ($H, D$ and $T$ are isotopes of hydrogen).