CBSE ADDA

SECTION - A   (Reading – 20 Marks)    1. Read the poem given below and complete the sentences that follow.   Just for a handful of silver he left us,   Just for a riband to stick in his coat-   Found the one gift of which fortune bereft us,   Lost all the others she lets us devote;   They, with the gold to give, doled him out silver,   So much was theirs who so little allowed;   How all our copper had gone for his service!   Rays- were they purple, his heart had been proud,   We that had loved him so, followed him, honoured him,   Lived in his mild and magnificent eye,   Learned his great language, caught his clear accents,   Made him our pattern to live and to die   He alone breaks from the van and the freemen,   He alone sinks to the rear and the slaves !                                                         Robert Browning   (A) The person who left them is their ___________ .   (B) He left them for the sake of __________ .   (C) The speaker and his comrades w

Q. 1. A concave mirror of focal length 20cm is placed 50 cm from a wall. How far from the wall an object be placed to form its real image on the wall?  Solution: V= -50 cm F= -20cm From mirror formula 1/u = 1/f – 1/v = -1/20+ 1/50 = - 3/100  U = - 33.3 cm Therefore, the distance of the object from the wall x =  50 – u X = 50 – 33.3 = 16.7 cm. Q.2. An object is placed at a distance of 40cm from a concave mirror of focal length 15cm. If the object is displaced through a distance of 20 cm towards the mirror, By how much distance is the image displaced? Answer: Here f = - 15 cm, u = - 40 cm Now 1/f = 1/u + 1/v Then 1/v = 1/f – 1/u Or V= uf/u-f =( - 40 x -15)/25 = -24 cm Then object is displaced towards the mirror let u1 be the distance object from the Mirror in its new position. Then u1 = -(40-20) = -20cm If the image is formed at a distance u1 from the mirror then v1 = u1f/u1-f = -20X-15/-20+15 = -60 cm. = - 20 x-15/-20+15 = -60 cm. Therefor

CBSE Science X Question paper of 2011 solution for preparation of 2014   1. What are the various steps in a food chain called? Solution: Trophic levels. 2. What is the important function of presence of ozone in earth’s atmosphere? Solution: The ozone layer prevents the harmful UV rays from entering into the earth’s atmosphere. 3. Write the electron dot structure of ethane molecule, C2H6 Self 4. What makes the earth’s atmosphere a heterogeneous mixture? Solution: Different gases like  oxygen, nitrogen, argon and CO 2 with other gases make the earth’s atmosphere a heterogeneous mixture. 5. List any four characteristics of a good fuel. Solution: Characteristics of a good fuel are : i. low ignition temperature. ii. High calorific value iii. Environmental friendly. iv. Easily available and accessible 6. What are non-renewable resources of energy? Give two examples of such resources. Solution: Non-renewable resources of energy are those energy resources t