<span>The number of the group identifies the column of the standard periodic table in which the element appears.</span>
Group 1 contains the  alkali metals ( lithium<span> (</span>Li<span>), </span>sodium<span> (</span>Na<span>), </span>potassium<span> (</span>K<span>), </span>rubidium<span> (</span>Rb<span>), </span>caesium<span> (</span>Cs<span>), and </span>francium(Fr).)<span>
Group 2 contains the alkaline earth metals (</span> beryllium<span> (</span>Be),magnesium<span> (</span>Mg<span>), </span>calcium<span> (</span>Ca<span>), </span>strontium<span> (</span>Sr<span>), </span>barium<span> (</span>Ba<span>) and </span>radium<span> (</span>Ra<span>) )
Group 3: </span><span> Scandium (Sc) and yttrium (Y) </span>
        
             
        
        
        
The total amount of energy remains constant in an isolated system. It implies that energy can neither be created nor destroyed, but can be change from one form to another.
 
        
             
        
        
        
A. Diagram A
B. Diagram C & D
C. Diagram B
D. Diagram C & D
E. Diagram B
F. Diagram C & D
These are simplified representations of an object's body and the force vectors acting on it. Some of the main forces that are involve are normal force, friction, push or pull and gravity.
        
             
        
        
        
consider the motion along the X-direction 
X = horizontal displacement = 80 m 
 = initial velocity along the x-direction = v Cos60
 = initial velocity along the x-direction = v Cos60
t = time of travel
using the equation 
X =  t
   t 
80 = (v Cos60) (t)
t = 160/v                                         eq-1
consider the motion in vertical direction :
Y = vertical displacement = 20 m 
 = initial velocity in Y-direction = v Sin60
  = initial velocity in Y-direction = v Sin60
a = acceleration = - 9.8 m/s²
t = time of travel = 160/v
using the equation 
Y =  t + (0.5) a t²
  t + (0.5) a t²
20 = (v Sin60) (160/v) + (0.5) (- 9.8) (160/v)²
v = 32.5 m/s