In which plant group is the gametophytic phase reduced,haploid,short-lived,and subterranean?

$\frac{1}{2}-\frac{1}{2 \cdot 2^2}+\frac{1}{3 \cdot 2^3}-\frac{1}{4 \cdot 2^4}+\ldots$ is equal to

$A$ particle of mass $m$ and charge $q$ is in an electric and magnetic field,given by $\vec{E} = 2 \hat{i} + 3 \hat{j}$ and $\vec{B} = 4 \hat{j} + 6 \hat{k}$. The charged particle is shifted from the origin to the point $P(1, 1)$ along a straight path. The magnitude of the total work done on it is: (in $q$)

Assertion $(A)$: Cyclohexane is the most stable cycloalkane.
Reason $(R)$: Cyclopropane and cyclobutane are less stable due to angle strain and torsional strain.
The correct answer is:

The compound which does not show paramagnetism is :-

If the circle $x^2+y^2+6x-2y+k=0$ bisects the circumference of the circle $x^2+y^2+2x-6y-15=0$,then $k$ is equal to