In the final answer of the expression $\frac{(29.2-20.2)(1.79 \times 10^5)}{1.37}$,the number of significant figures is:

The inverse point of $(1,2)$ with respect to the circle $x^2+y^2-4x-6y+9=0$ is

$A$ number $n$ is chosen at random from $S=\{1, 2, 3, \ldots, 50\}$. Let $A=\{n \in S: n+\frac{50}{n} > 27\}$,$B=\{n \in S: n \text{ is a prime}\}$ and $C=\{n \in S: n \text{ is a square}\}$. Then,the correct order of their probabilities is

If the foci of the ellipse $\frac{x^2}{25}+\frac{y^2}{16}=1$ and the hyperbola $\frac{x^2}{4}-\frac{y^2}{b^2}=1$ coincide,then $b^2$ is equal to

If $(2,-1,3)$ is the foot of the perpendicular drawn from the origin to the plane,then the equation of the plane is

The $P-V$ diagram of a diatomic gas is a straight line passing through the origin. The molar heat capacity of the gas in the process will be: