Answer:
(a) 
(b) 
Explanation:
(a)
Volume, V of unit cell
Number of unit cells, N
Where 
is weight of material and 
is density of material
(b)
Number of atoms in paper clip
This is a product of number of unit cells and number of atoms per cell
Since iron has 2 atoms per cell
Number of atoms of iron=
Express it in standard form and apply the basic indices laws to simplify
Answer:
The correct answer is option 'B': Load is far from fulcrum and the effort is applied near the fulcrum
Explanation:
A lever works on the principle of balancing of torques. The torque about the fulcrum by the load should be equal to the torque by the applied effort. Since we know that the torque is proportional to both the force and the distance it is applied from the distance from the axis of rotation. A lever is used when we need to lift a heavy load by utilizing this effect of the lever arm.
A mechanical disadvantage occurs when we are not able to lift the weight easily due to the fact we apply effort near the fulcrum.
