Observe the following statements :
$I$. The circle $x^2+y^2-6x-4y-7=0$ touches the $y$-axis.
$II$. The circle $x^2+y^2+6x+4y-7=0$ touches the $x$-axis.
Which of the following is a correct statement?

What is the use of Guayule ($Parthenium$ $argentatum$)?

What is the biological concentration of $DDT$ in the body fat of Indian people?

The circle $4x^2 + 4y^2 - 12x - 12y + 9 = 0$

Regarding the molecular orbital $(MO)$ energy levels for homonuclear diatomic molecules, the $\text{INCORRECT}$ statement$(s)$ is$($are$)$
$(A)$ Bond order of $Ne _2$ is zero.
$(B)$ The highest occupied molecular orbital $\text{(HOMO)}$ of $F_2$ is $\sigma$-type.
$(C)$ Bond energy of $O _2^{+}$is smaller than the bond energy of $O _2$.
$(D)$ Bond length of $Li _2$ is larger than the bond length of $B _2$

At identical temperature and pressure,the rate of diffusion of hydrogen gas is $3\sqrt{3}$ times that of a gaseous hydrocarbon having molecular formula $C_nH_{2n-2}$. What is the value of $n$?