The correct structure of the drug paracetamol is

Shreya read in her textbook that communicable diseases are caused by pathogens. These pathogens pass from patients to healthy persons causing the disease. She suggested her friends that we can prevent the spread of these diseases and even some of them can be eradicated.

$(a)$ What are the various methods of spread of communicable diseases?

$(b)$ What preventive measures can be taken to prevent the spread of communicable diseases?

$(c)$ Which values are displayed by Shreya in taking initiative ?

$(d)$ Suggest some school activity to promote such values in school students ?

If $x$ is a solution of the equation $\sqrt{2x+1} - \sqrt{2x-1} = 1$ for $x \geq \frac{1}{2}$,then $\sqrt{4x^2-1}$ is equal to:

$A$ thin semi-circular ring of radius $r$ has a positive charge $q$ distributed uniformly over it. The net electric field $\vec{E}$ at the center $O$ is:

$A$ straight conductor of length $4 ~m$ moves at a speed of $10 ~m/s$. When the conductor makes an angle of $30^{\circ}$ with the direction of the magnetic field of induction $0.1 ~Wb/m^2$,the induced emf is: (in $~V$)

If $A$ and $B$ are mutually exclusive events with $P(B) \neq 1$,then $P(A \mid \bar{B})$ is equal to (Here $\bar{B}$ is the complement of the event $B$)