Atomic size decreases across a period due to an increase in the effective nuclear charge. true or false

True

Explanation:

Along a period from left to right  the atomic size decreases because all the electrons are subsequently added to the same shell, also the equal no. of protons are added to the nucleus leading to the increase in the net effective nuclear charge at the constant distance. This leads to the increase in the force of attraction between the (opposite) charged particles which shrinks the atomic size.

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