According to Graham's law,the rate of diffusion of $CO$,$O_2$,$N_2$,and $CO_2$ follows the order:

At $27^{\circ} C$,a closed vessel contains a mixture of equal weights of helium (mol. wt. = $4$),methane (mol. wt. = $16$) and sulphur dioxide (mol. wt. = $64$). The pressure exerted by the mixture is $210 \ mm$. If the partial pressures of helium,methane and sulphur dioxide are $p_1, p_2$ and $p_3$ respectively,which one of the following is correct?

$X -$ In deep-sea hydrothermal vents,the average temperature is significantly higher than $25$ to $30^{\circ} C$.
$Y -$ Reptiles and amphibians are ectotherms (poikilotherms),not eurythermal.

Which of the following statements is true for transition elements?

$A$ reversible engine converts one-sixth of the heat supplied into work. When the temperature of the sink is reduced by $62^{\circ} C$,the efficiency of the engine is doubled. The temperatures of the source and sink are

The triangle formed by the lines $2x^2+xy-6y^2=0$ and $x+y-1=0$ is