Answer:
a.They have a smaller proportion of heavy elements.
Explanation:
As a  star grows old , its metal content becomes low . Our sun is Population I star which means it is very new . Its metal content is 1.4 % . By the term metal we mean any element heavier than helium . Population II stars are older than population I stars . They will have lesser content of metal . Population III are oldest star group which have metal content as less as .015 % . 
 
        
             
        
        
        
Answer:
Wg is positive and WT negative.
(Letters in options are all wrongly written).
Explanation:
Remember that the work of a force is the internal product between the force and the displacement  .
.
Since the displacement is downwards like the weight, the work done by gravity is positive, while the work done by the tension is negative since it points upwards.
 
        
             
        
        
        
In case of an object sitting at rest on another base, there are two equal and opposite forces – Normal force and the gravity.
Answer: Option A
<u>Explanation:
</u>
When an object is placed at rest position on another object, there is a force exerted by the surfaces of the two contact objects. This force is denoted as Normal Force.
When an object such as a box is placed on a shelf, its surface exerts a contact force on the base of the shelf- The Normal force directed upward. Meanwhile, the gravity stays at its action and tries to pull the box towards itself.  
Both of these forces however are equal and opposite and therefore, there is zero net force on the box. That's why it remains at rest, holding on Newton's third law.
 
        
             
        
        
        
The turns ratio is equal to the voltage ratio. Let n1 and n2 be the primary and secondary turns. Then
5850V/120V=n1/n2
48.75=2680/n2
n2=2680/48.75
n2=55