The answer is
D. Covalent bond
Hope this helps you have a great day.
Answer:
The correct option is;
X, W, Y, Z
Explanation:
The parameters given are;
Spring (S), Spring Constant (N/m)
W, 24
X, 35
Y, 22
Z, 15
The equation for elastic potential energy, 
, is 
The above equation can also be written as 
Where:
k = The spring constant in (N/m)
x = The spring extension
Therefore, since the elastic potential energy, , of the spring is directly proportional to the spring constant, k, we have the springs with higher spring constant will have higher elastic potential energy, , therefore the correct order is as follows;
X > W > Y > Z
I think the answer is (1) Co. Because the element of Cobalt also has 2 electrons at the outer layer which is the same as Calcium. And the outer layer is an important factor which can affect the property of an element.
Mass = no. of moles x molecular weight
m = n x Mr
m = 2.5 mol x (24 + [16 x 2])
m = 140g
