In a permanent magnet at room temperature,

Which of the following hydrides is electron-deficient?

In a hydrogen atom,an electron of charge $e$ revolves in an orbit of radius $r$ with speed $v$. Then,the magnetic moment associated with the electron is

$A$ uniform rope of length $L$ and mass $m_1$ hangs vertically from a rigid support. $A$ block of mass $m_2$ is attached to the free end of the rope. $A$ transverse pulse of wavelength $\lambda_1$ is produced at the lower end of the rope. The wavelength of the pulse when it reaches the top of the rope is $\lambda_2$. The ratio $\lambda_2/\lambda_1$ is

$\int_{-2}^2 |[x]| \, dx$ is equal to

Heroin is chemically known as $.........$.