SCIENCE AND TECHNOLOGY (Theory) 2007
Time allowed: 3 hours; Maximum Marks: 100
question paper comprises of two sections A and B. You are to attempt both sections.
||You are advised to attempt all the questions of Section A and Section B separately.
|| All questions are compulsory.
||There is no overall choice. However, internal choice has been provided in some questions. You are to attempt only one option in such questions.
|| Marks allocated to every question are indicated against it.
||Questions number 1-4 in Section A and 17, 18 in Section B are very short answer questions. These are to be answered in one word or one sentence.
||Questions number 5-8 in Section A and 19, 20 in Section B are short answer questions. These are to be answered in 30 - 40 words each.
||Questions number 9-14 in Section A and 21 - 23 in Section B are also short answer questions.These are to be answered in 40 - 50 words each.
||Questions number 15, 16 in Section A and 24 in Section B are long answer questions. These are to be answered in 70 words each.
SECTION - A
1. The pH values of three solutions A, B and C having equal molar concentration are respectively 2.0, 7.0 and 13.0 at 298 K. Which of the three solutions represents an acid solution?
Write the chemical formula of simplest ketone.
3. Why is our galaxy called ‘Milky Way’ ?(Out of syllabus)
4. If the distance between two electric charges is doubled, how much will the force exerting between them change to?
State four characteristic features of ‘Dynamic Equilibrium’. (Out of syllabus)
What is Fehling’s reagent? What would you observe on heating formalin with Fehling’s reagent in a test tube? (Out of syllabus)
Distinguish between a ‘geosynchronous’ and a ‘polar’ satellite. What is the usual time period of a (Out of syllabus)
(a) geosynchronous satellite?
8. An electric heater is used on 220 V supply and takes a current of 3.4 A. Calculate (i) its power and (ii) its resistance, when it is in use.
9. What is ‘plaster of Paris’ chemically? How is it obtained from gypsum? Write the condition and chemical equation involved in its manufacture.
10. Define the term, ‘allotropy’. In which kind of properties are the two allotropes of an element (i) similar, (ii) different? How can the two allotropes of sulphur be distinguished from one another? (Outofsyllabus)
Give reasons for the following
(i) Alcohol supplied for an industrial purpose is mixed with poisonous substances like copper sulphate solution.
i) Copper sulphate imparts blue colour to alcohol, hence, it becomes easier to identify alcohol meant for industrial purpose. To prevent misuse of industrial alcohol, it is denatured with methanol and copper sulphate. Methanol makes it poisonous, and copper sulphate imparts blue colour.
12. A convex mirror used on a bus has a focal length of 200 cm. If a scooter is located at 400 cm from this mirror, find the position, nature and magnification of the image formed in the mirror.
(a) What is a ‘solar cell’ ?
(b)Why biogas is considered an ideal fuel for domestic use?
(c) Name a device in which controlled chain reaction is used.
14.(a) Define the term, ‘electroplating’.
(b) With a labelled diagram describe an activity to show copper plating on a metal spoon. (Outofsyllabus)
15. (a) Write the name and formula of the main ore of aluminium.
(b) What is alumina? Which reducing agent is used for the reduction of alumina?
(c) Draw a diagram of the electrolytic cell used in the reduction of alumina. Label anode and cathode on it.
(d) Why is alumina dissolved in cryolite? (Outofsyllabus)
(a) What is an alloy? How is an alloy made?
Name an alloy
Which has a lower melting point than its constituents?
Which is more hard, tough and strong than its constituents?
16. Name the four common defects of vision and state the cause of each defect. A person cannot see distinctly objects placed beyond 2 meters. State the nature and focal length of the lens which could be used to correct this defect.
(a) Describe with diagram an experiment to show that a force is exerted on a current carrying conductor when placed perpendicular in a magnetic field.
(b) State the rule to find the direction of the force exerted on a current carrying conductor in a magnetic field.