What type of polymer is natural rubber?

$A$ positively charged $(+q)$ particle of mass $m$ has kinetic energy $K$ and enters a region with a horizontal magnetic field of induction $\vec{B}$ in a vertically downward direction. The acceleration of the particle is:

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).

What will be the volume of $CO_2$ at $NTP$ obtained on heating $10 \ g$ of ($90\%$ pure) limestone (in $L$)?

An ion $M^{2+}$ forms the complexes $[M(H_2O)_6]^{2+}$,$[M(en)_3]^{2+}$,and $[MBr_6]^{4-}$. Match the complex with the appropriate colour.

If $x + by + c = 0$ is a normal to the parabola $y^2 = 12x$,then the complete set of all values of $c$ is -