Atoms of elements at the top of a group on the periodic table are smaller than the atoms of elements at the bottom of the group. How does this help explain the difference in the reactivity of metals within a group? Answers
1.The valence electrons of the larger atoms are farther from the nucleus and are easier to remove, so the metals near the top are more reactive than those at the bottom.
2.The valence electrons of the larger atoms are farther from the nucleus and are harder to remove, so the metals near the bottom are more reactive than those at the top.
3.The valence electrons of the larger atoms are farther from the nucleus and are harder to remove, so the metals near the top are more reactive than those at the bottom.
4.The valence electrons of the larger atoms are farther from the nucleus and are easier to remove, so the metals near the bottom are more reactive than those at the top.

falling water hydro = water .. spectcular places these plants are

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electromagnetic shielding is the practice of reducing the electromagnetic field in a space by blocking the field with barriers made of conductive or magnetic materials. shielding is typically applied to enclosures to isolate electrical devices from their surroundings, and to cables to isolate wires from the environment through which the cable runs. electromagnetic shielding that blocks radio frequency electromagnetic radiation is also known as rf shielding.

the shielding can reduce the coupling of radio waves, electromagnetic fields and electrostatic fields. a conductive enclosure used to block electrostatic fields is also known as a faraday cage. the amount of reduction depends very much upon the material used, its thickness, the size of the shielded volume and the frequency of the fields of interest and the size, shape and orientation of apertures in a shield to an incident electromagnetic

from wikipedia

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