A conductor (shown in the figure) carrying constant current I is kept in the x-y plane in a uniform magnetic field →B. If F is the magnitude of the total magnetic force acting on the conductor, then the correct statement(s) is (are): if →B is along ẑ, F∝(L+R); if →B is along ẋ, F=0; if →B is along ŷ, F∝(L+R); if →B is along ẑ, F=0

The vector sum of all current element in wires not parallel to x axis will lead to resultant current element of length R and current along x axis. Total length of current element: dl=2(L+R)^x →F=i(2(L+R)^x) × →B
If →B along ^z then F will be along −^y and will be propotional to (L+R)
If →B along ^x then F=0 since vector product is zero.
If →B along ^y then F will be along ^z and will be prop to (L+R)
If →B along ^z then F will be along −^y and will not be equal to 0.