In a compound,$C$,$H$,and $N$ atoms are present in the ratio $9 : 1 : 3.5$ by weight. The molecular weight of the compound is $108$. Its molecular formula is:

Let $P$ be a plane passing through the points $(2,1,0)$,$(4,1,1)$ and $(5,0,1)$ and $R$ be the point $(2,1,6)$. Then the image of $R$ in the plane $P$ is

The point at which the circles $x^2+y^2-4x-4y+7=0$ and $x^2+y^2-12x-10y+45=0$ touch each other is:

$\int_0^3 \frac{3x+1}{x^2+9} dx$ is equal to :

$A$ positively charged $(+q)$ particle of mass $m$ has kinetic energy $K$ and enters a region with a horizontal magnetic field of induction $\overrightarrow{B}$ in a vertically downward direction. The acceleration of the particle is:

$A$ body executes simple harmonic motion under the action of a force $F_1$ with a time period $T_1 = \frac{4}{5} \ s$. If the force is changed to $F_2$,it executes $SHM$ with a time period $T_2 = \frac{3}{5} \ s$. If both the forces $F_1$ and $F_2$ act simultaneously in the same direction on the body,what is its new time period in seconds?