When acetamide reacts with $Br_2$ and caustic soda,then we get:

$x=\cos ^{-1}\left(\frac{1}{\sqrt{1+t^2}}\right), y=\sin ^{-1}\left(\frac{t}{\sqrt{1+t^2}}\right) \Rightarrow \frac{d y}{d x}$ is equal to

The atomic numbers of elements $X, Y$ and $Z$ are $19, 21$ and $25$ respectively. The number of electrons present in the $M$-shell of these elements follow the order:

The element with atomic number $12$ belongs to ......... group and ......... period.

The period of a simple pendulum,whose bob is a hollow metallic sphere,is $T$. The period is $T_1$ when the bob is filled with sand,$T_2$ when it is filled with mercury,and $T_3$ when it is half-filled with mercury. Which of the following is true?

Which of the following is an example of a Gram-positive bacterium?