Science
- Give scientific reason Graphite is not used in ornaments. Graphite is a black, soft, brittle and dull form of carbon. It is neither malleable nor ductile. These properties of graphite make it unsuit... 1
- write scientific reason Graphite is a conductor of electricity. In graphite, each carbon is bonded to three other carbon atoms in such a way that a hexagonal layered structure is formed. Due to this struc... 1
- Difference between Crystalline and non-crystalline forms of carbon Crystalline forms of carbon Non-crystalline forms of carbon (i) A crystalline form has a regular and definite arrangement of atoms. (ii) The... 1
- difference between Diamond and graphite. Diamond Graphite (i) Diamond is a brilliant, hard and crystalline allotrope of carbon. (i) Graphite is a black, soft, brittle and slippery c... 1
- Write the uses of diamond? Uses of diamonds are: Diamonds are used in glass cutting and rock drilling machines. Diamonds are used in ornaments. Diamond knives are used... 1
- In which compounds forms does carbon occurs? Carbon exist in various forms in its compounds. Some of the carbon compounds are as follows. In hydrocarbons mainly hydrogen and carbon are... 1
- Why are carbon and it’s compounds are used as fuel? As carbon and it’s compounds after combustion produces large amount of heat and also energy. So to gain more heat and energy carbon and it’s... 1
- Select the proper options and complete the statement. (Single, all, double, ionic, carbon, give and take, hydrogen) a) A carbon atom forms a covalent bond with other atoms. In this bond the two atoms share b) All the bonds in a saturated hydrocarbon share... 1
- Helium gas is filled in two identical bottles A and B. The mass of the gas in two bottles is 10g and 40g respectively. Given that, Mass of gas in bottle = m = 10 g Mass of gas in bottle = M= 40 g speed of sound in bottle A =speed of sound in bottle B = V Temp... 1
- Hydrogen gas is filled in two identical bottles, A and B at the same temperature. The mass of hydrogen in Given, mass of bottle A= m = 12 g mass of bottle B = M = 40 g Let us suppose speed of sound in bottle A = v And speed of sound in bottle B =... 1
- Sunil is standing between two parallel walls. The wall closest to him is at a distance of 660m. If he shouts, he hears Given that, The distance of wall closest to him is 660 m. And first echo will be heard after 4 seconds. 1) Thus, distance travelled by the s... 1
- Nita heard the sound of lightning after 4seconds of seeing it. What was the distance of lightning from her? Given that velocity is sound in air is 340m/s. And Nita heard sound of lightning after 4seconds. Hence, the distance of lightning from Nita... 1
- The speed of sound in air at 0°C is 332m/s. If it increases at the rate of 0.6m/s per degree, Let T be the temperature at which velocity of sound is 344m/s. Then the velocity of sound increased from 0°C to T°C would be = 344 - 332= 12... 1
- Where and why sound absorbing materials are used? The sound absorbing materials are used in constructing the roofs and walls of conference halls, auditorium halls and theatre so that the sou... 1
- What should be the dimensions and the shape of classrooms so that no echo can be produced there? The dimensions of classroom should be made such that we can’t hear an echo is the classroom should be square shaped and the distance between... 1
- Study the construction of the Golghumat at Vijapur and discuss the reasons for the multiple echoes produced there. Goighumat with a height of 51 metres and diameter of 37 metres with 3 metres thick walls is spread over approximately 1700 square metres. Th... 1
- What is an echo? What factors are important to get distinct echo? An echo is the repetition of the original sound because of reflection by some surface. At 22°C, the velocity of sound in air is 344 m/s. Our... 1
- We cannot hear an echo produced in a classroom. Our classrooms are mostly constructed in a such way that the distance between two walls of the classroom would be less than 17m. When there... 1
- The intensity of reverberation is higher in a closed and empty house. In a closed and empty room there will be no objects like furniture and other things. Due to which the sound generated reflects from the wall... 1
- The roof of a movie theatre and a conference hall is curved. The roof of movie theatre and a conference are made curved because when sound is reflected from curved roof and also from walls, it reach to... 1
- Fill in the blanks and explain. a) Sound does not travel through vacuum. Since, sound waves are longitudinal waves which requires medium for their propagation and hence doe... 2
- When a person stands in front of a plane mirror, how is the image formed? What is the nature of the image? The image of a person is formed from every point of the source, thereby forming an extended image of the whole source. The image formed woul... 1
- Which letters of the English alphabet form images that look the same as the original letters? A, H, I, M, O, T, U, V, W, X, Y 2
- If we hold a page of a book in front of a mirror, we see laterally inverted letters in the mirror. Why does it happen? When we hold a page of a book in front of the mirror, the image of the words appear laterally inverted. The image of every point of the word... 1