Noble Metals

1. What are noble metals? Give two examples of noble metals.
2. Why do noble metals not get tarnished?
3. Why are gold and platinum used for making jwellery?
4. Write two uses each of gold and platinum.
5. Why can we not make jwellery of pure gold?
6. How is purity of gold expressed?
7. What do you mean by 22 carat gold?

Comments

Post a Comment

Popular posts from this blog

Combustion

1. Gaseous fuels are considered the best.Write four poins in support of your answer. 2. What causes smog in winters? 3. If the amount of carbon dioxide increases in the atmosphere,what can be the effects of it? 4. What is global warming? Write it's one useful and one harmful effect of it. 5. What is acid rain? Write it's two harmful effects. 6. What is CNG?  Write three uses of CNG.
Read more

CELL CLASS-8

Image
1.What is a cell ? 2.Why are cells known as building blocks of life ? 3.Cell is basic structural and functional unit of life.Explain the statement. 4.What are unicellular organisms ? 5.Define multicellular organisms. 6.Name two unicellular organisms. 7.Name two multicellular organisms. 8.Who observed cell for the first time ? 9.Why do organisms differ in size ? 10.Why do different organisms have different shapes ? 11.Name the smallest cell. 12.Name the longest cell. 13.Name the largest cell. 14. Why do nerve cell posses a long fiber-like structure ? 15.Write the full form of PPLO. 16.What is the importance of yolk in hen`s egg ? 17.What is the life span of red blood cell ? 18.Name the stain used to stain human cheek cell ? 19.Name the stain for onion peel cell ? 20.White blood cell is like an organism.Name the organism. 21.What are cell organelles ? 22.Name the outer covering of an animal cell ? 23.What is a cell wall ? 24.Write 2 functions of cell wall ? 25
Read more

Combustion

1. If you hold a long copper wire in a candle flame, copper wire gets red hot in the non - luminous part whereas it just gets blackened in the luminous part. Why? 2. Goldsmiths often use a mettalic blow to direct non luminous part of flame on gold to give shape to gold ornaments. Why? 3. You observe circular greyish black ring formed on the glass slide in which there is no deposition in the middle of the ring. Why? 4. Water should not be used to extinguish fire caused by electric short circuit. Justify your statement. 5. Two paper cups, one filled with water and other empty, are heated over a bunsen burner. Empty cup catches fire immediately whereas the other does not. Why?
Read more