If a charge projected in a zero gravity region, find the possible cases of electric and magnetic fields in that region so no net force exerts on charge,

(a) $E=0\text{,} B=0$
(b) $E=0\text{,} B\ne 0$
(c) $E\ne 0\text{,} B\ne 0$
(d) $E\ne 0\text{,} B=0$

If a projected charge passes through a zero gravity region without change in its velocity, then find possible cases of electric and magnetic field in that region:
(a) $E=0\text{,} B=0$
(b) $E=0\text{,} B\ne 0$
(c) $E\ne 0\text{,} B\ne 0$
(d) $E\ne 0\text{,} B=0$

If a projected charge passes through a zero gravity region and remains undeviated or undeflected, then find possible cases of electric field and magnetic field in that region.

(a) $E=0\text{,} B=0$
(b) $E=0\text{,} B\ne 0$
(c) $E\ne 0\text{,} B\ne 0$
(d) $E\ne 0\text{,} B=0$

If a projected charge passes through a zero gravity region, its speed may be constant. Then, find the possible cases of electric and magnetic fields in that region.

(a) $E=0\text{,} B=0$
(b) $E=0\text{,} B\ne 0$
(c) $E\ne 0\text{,} B\ne 0$
(d) $E\ne 0\text{,} B=0$

A magnetic field is applied perpendicular to the axis of cylindrical discharge tube. Then, cathode and positive rays are deflected in,

There is a magnetic field acting in a plane perpendicular downwards. A particle in vacuum moves in the plane of paper from left to right as shown in figure. The path indicated by the arrow could be due to,