D. Answer the following questions :
1. What is meant by the term electroplating.
2. How can a thin layer of silver be deposited on a brass spoon?
3. What is a contact force? Give two examples.
4. What do you know about nuclear membrane?
5.
How can you say that protoplasm is a living material?
6. What is meant by the calorific value of a fuel?
7. How is charcoal made?
8. Distinguish between light and heavy metal.
9. Describe the general structure of a bacteria.
10. What is meant by transplantation?
Answers
Answer:
A1)coat (a metal object) by electrolytic deposition with chromium, silver, or another metal.
A2)The process of depositing a thin layer of any superior metal over an object of a cheaper metal, with the help of electric current is called electroplating. For example; deposition of silver on brass or copper objects and that of copper, nickel, chromium etc., on objects made of iron is done by electroplating
A3)A contact force is any force that requires contact to occur. Contact forces are ubiquitous and are responsible for most visible interactions between macroscopic collections of matter. Pushing a car up a hill or kicking a ball across a room are some of the everyday examples where contact forces are at work.
A4)A nuclear membrane is a double membrane that encloses the cell nucleus. It serves to separate the chromosomes from the rest of the cell. The nuclear membrane includes an array of small holes or pores that permit the passage of certain materials, such as nucleic acids and proteins, between the nucleus and cytoplasm.
A5)hey are together called protoplasm. nucleus acts as the boss of cell,helps in cell division, makes proteins,etc. cytoplasm contains cell organelles and cell membrane allows entry and exit of materials.so protoplasm is called'living part of the cell'. it performs funtions cell wall found in plants is dead part.
A6)The calorific value of a fuel is the number of heat units evolved when unit mass (or unit volume in the case of a gas) of a fuel is completely burned and the combustion products are cooled to 298 K.
A7)Charcoal is a lightweight black carbon residue produced by strongly heating wood (or other animal and plant materials) so as to drive off all water and other volatile constituents. ... Charcoal can also be produced by heating the material in a closed retort.
A8)From 1809 onward, light metals, such as magnesium, aluminium, and titanium, were discovered, as well as less well-known heavy metals including gallium, thallium, and hafnium. ... As well as being relatively dense, heavy metals tend to be less reactive than lighter metals and have far fewer soluble sulfides and hydroxides.
A9)Structure. Bacteria (singular: bacterium) are classified as prokaryotes, which are single-celled organisms with a simple internal structure that lacks a nucleus, and contains DNA that either floats freely in a twisted, thread-like mass called the nucleoid, or in separate, circular pieces called plasmids.
A10)the process of taking an organ or living tissue and implanting it in another part of the body or in another body.