You'll need a helper variable for this, so depending on your programming language, the solution becomes:
int helper;
helper = arr[i];
arr[i] = arr[j];
arr[j] = helper;
 
        
             
        
        
        
<h2>Many properties can be listed out viz. durability, quality, the sound that it produces also depends on the material that is used, etc.</h2>
Explanation:
1. If you take wood then I would say maple, rosewood, cedar, walnut can be used to make "String instruments". 
Reason: 
The wood that we choose should be perfect and should give long-life to use the instrument.
2. If we consider about strings, then I would suggest that the material that you choose should be "ductile and hard".
Reason:
Thin wires can be drawn. 
3. In case of Brass, it should be "malleable metal", so that the outcome of the instrument will satisfy the need.
 
        
             
        
        
        
A service company would hire an Information Support and Service employee.
hope it helps you!