Which nucleus completes the following equation?

B is correct.

Explanation:

Given the equation

According to alpha emission

Alpha emission is a radioactive decay in which the atomic nucleus emit the alpha particle and formed a new nucleus whose mass number reduced by four and atomic number reduced by two.

Therefore,

Po is the new nucleus.

Where, Rn = Radon

Po= polonium

he made 11 calls in one day

weight of the box is given as

here this is placed on the inclined of angle 42 degree

now this weight will have two components one is along the incline other is perpendicular to it

so here we need to apply a force parallel to incline opposite to its component of weight

so here the component of weight is given as

here we have

so it requires 75 n force to move it upwards