Which of the following will not show deflection from the path on passing through an electric field?

The positron was discovered by

The $\alpha$-particle is identical with

Which one of the following pairs is not correctly matched?

$A$ particle having the same charge and $200$ times greater mass than that of an electron is:

Which of the following statements is correct about the cathode rays?
$1$. These rays start from anode and move towards cathode.
$2$. They are visible with human eye.
$3$. In presence of electric and magnetic fields,they behave like positively charged particles.
$4$. Their characteristic does not depend on the nature of material at electrode.