The major product of the following reaction is:

This is the $1^{st}$ and $2^{nd}$ exam question.

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 ?

When carbon monoxide is passed over solid caustic soda heated to $200^\circ C$,it forms

What will be the $pH$ of an aqueous solution of $1.0 \ M$ ammonium formate? (Given: $pK_{a}=3.8$ and $pK_{b}=4.8$)

The difference between the radii of $n^{\text{th}}$ and $(n+1)^{\text{th}}$ orbits of a hydrogen atom is equal to the radius of the $(n-1)^{\text{th}}$ orbit of hydrogen. The angular momentum of the electron in the $n^{\text{th}}$ orbit is . . . . . . ($h$ is Planck's constant).