The common name to the family member of phylum Echinodermata of marine family is echinoderm. They are usually characterized by a five-fold symmetry, and possess an internal skeleton of calcite plates. They are found at every ocean depth.
The features of all adult echinoderm are:
- They have a five-fold symmetry.
- Body without segmentation.
- Spiny skin.
- Internal skeleton.
- found at every ocean depth.
Work done by me for using force of 4 N to push an object 3 m away is 12 J.
<u>Explanation:</u>
Work done on any object is defined as the force required to displace that object from its original position. In other terms, the work done is the measure of force utilized for moving an object. So mathematically it is represented as the product of force with the displacement of the object due to that force.

Then, here it is given that force of about 4 N is used to displace the object to 3m. Thus,

So, 12 J of work is done by me to push an object 3 m away with the force of 4 N.
Option D.
A voltaic cell need tha anode, the cathode and the electrolyt to work.
Volitmeter is just an equipment to measure the functioning of the voltaic cell.