The radius of an atom is of the order of

$A$ particle of mass $M$ at rest decays into two particles of masses $m_1$ and $m_2$ having non-zero velocities. The ratio of the de-Broglie wavelengths of the particles,$\lambda_1/\lambda_2$ is

$A$ satellite of mass $m$ is in a circular orbit of radius $2R_E$ about the Earth. The energy required to transfer it to a circular orbit of radius $4R_E$ is (where $M_E$ and $R_E$ are the mass and radius of the Earth respectively).

In the following reaction,$X$ and $Y$ are respectively:
$CH_3COOH + NH_3$ $\longrightarrow X \stackrel{\Delta}{}$ ${\longrightarrow} Y + H_2O$

Assertion $(A)$: Optical fibres are widely used in communication networks. Reason $(R)$: Optical fibres are small in size,light in weight,flexible,and there is no scope for interference in them.

What is the use of Guayule ($Parthenium$ $argentatum$)?