May 252015
 


Time: 3 hours

Full Marks: 100
Pass Marks: 35

Answer all the questions.

1. a) Put the following words in alphabetical order. [2]
recent, recover, reclusive, real, record, recoil

b) Choose the correct guide words for each headword. [3]

Head Word Guide Word
i) wither
ii) ghee
iii) pinch
i) wise/witness
ii) witter/wood
iii) gesture/get
iv)getaway/giddy
v) pilot/ping
vi) pink/pit

2. a) Choose the appropriate word from the brackets. [3]
i) The new rule will come into …… (affect, effect) from the next month.
ii) Mr. Thapa is the …… (principal, principle) of this campus.
iii) He purchased a dozen of pencils from the …… (stationery, stationary) shop.
iv) You have to …… (practise, practice) all the grammatical exercises given in your textbooks.
v) Don’t take your teachers’ …… (advice, advise) for granted.
vi) The …… (new, knew) chairman will start his work from tomorrow.

b) Write the antonyms of the following words: [2]
i) cheerful      ii) fast      iii) near      iv) regular

3. Write a dialogue between two friends describing their first day in college. [5]

4. Answer any two of the following questions. [10 × 2 = 20]
a) Narrate the story of ‘The House Call’. (The House Call)
b) What changes does the poet notice when he returns to the poplar fields after a long time? (The Poplar Field)
c) What are Barbara Holland’s opinions about single and multiple children? Describe. (Speaking of Children)

5. Give short answers to any three of the following questions: [3 × 5 = 15]
a) What are the features of migraine headaches? (In Bed)
b) What are the obstacles faced by Phoenix Jackson on her way to the city? (A Worn Path)
c) Into what groups has Rosenblatt organized his numerous examples of verbal mis-steps? (Oops! How’s That Again)
d) Would you call Supriya a betrayer? Give reasons for your answer. (Malini)

6. Write appropriate prepositions in the gaps. [10 × 0.5 = 5]
a) When the bull began to run …… me, I jumped …… the fence …… the next field.
b) She ran …… the corridor, and …… the stairs into the basement.
c) His bullet whistled …… me ear, so I shot him right …… the eyes.
d) The prisoner jumped ….. the window, ran …… the street, and jumped …… a car that was waiting for him on the other side.

7. Read the following conversations between A and B, and make similar conversations beginning with the sentences given in each. [5 × 1 = 5]
Example:
A: He works hard, doesn’t he?
B: Oh! I don’t know, I work much harder than he does.
A: Of course – nobody works as hard as you do.

a) He gets up early, doesn’t he?
b) She played well, didn’t she?
c) They live dangerously, don’t they?
d) She behaved badly, didn’t she?
e) He can dance beautifully, can’t she?

8. Read the following illustration, and make similar conversations based on the remarks. Use the points or periods of time given. [5 × 1 = 5]
Example: I know your sister. (September)
A: How long have you known her?
B: I’ve known her since September.
C: (to A) When did he meet her?
A: He met her in September.

a) I’m engaged now, you know. (July)
b) I’ve got a movie camera. (Christmas)
c) My leg’s hurting. (8 o’clock this morning)
d) I know that joke already. (years and years)
e) I’m a graduate now. (a fortnight)

9. Read the following example and change the sentences given in the same way. [5 × 1 = 5]
a) With although/even though      b) With in spite of/despite
Example: He looked very scruffy, he got the job.
A: Although/Even though he looked very scruffy, he got the job.
B: In spite of/Despite his scruffy appearance, he got the job.

a) She was 85 years old, but she still lived a very active life.
b) Her parents objected, but she still insisted on getting married.
c) The acoustics in the hall is poor, but it is still regularly used for concerts.
d) We’ve known each other for a long time, but we still call each other by our surnames.
e) Video machines are expensive, but lots of people are buying them.

10. Answer any two of the following: [2 × 10 = 20]
a) Write an account of the most important event in the history of your country. (about 150 words)
b) Write a letter to your friend whom you have not seen for a long time. Tell him/her what you and your family are doing these days.
c) Write a brief geographical description of your country. Include only important and interesting information. (about 150 words)

11. Read the following passage and answer the questions given. [5 × 2 = 10]

In London, I get up every morning at 7:00 AM. I’m not allowed to get up any later because I have to prepare breakfast for the children. Sometimes they drink milk, but they prefer to drink tea, so usually I make tea with bread and eggs. After the children have eaten breakfast, I walk with them to their school. After that, I return to the house and clean it. On Wednesdays, I have to wash the children’s clothes and sometimes they ask me if I can wash the car as well.
At 3:00 o’clock, I have to collect the children from school. I would like to help them with their housework, but their parents won’t let me. In the evening, we eat a yummy dinner that tastes really good. After dinner, I am allowed to go out. I like to go and watch films in the local cinema. I don’t have to work on Saturday or Sunday. Then I visit interesting places around London.

Questions:
a) What does an au pair boy do?
b) Why is he not allowed to get up later than 7am?
c) Why doesn’t Gautam help with the children’s homework?
d) What does he do after dinner?
e) Do you think Gautam likes being an au pair in London? Give reasons for your answer.


Jan 282014
 


Different reactions take place with different rates. The branch of physical chemistry that deals with the study of rate of chemical reaction is called chemical kinetics.
During chemical reaction, concentration of reactants decreases while that of product increases. Thus, the rate of reaction may be defined as the decrease in the concentration of reactant or the increase in the concentration of product per unit time.

Let us consider a reaction,
A → B
When time (t) = t1, (A)1 → (B)1
When time (t) = t2, (A)2 → (B)2
If t2 > t1,
Rate of reaction = – (A)2 – (A)1/t2 – t1 = +(B)2 – (B)1/t2 – t1

Here, the negative sign indicates that the concentration of reactants decreases with time. The rate of reaction is measured in molL-1sec-1.

Factors affecting rate of reaction

There are many factors affecting the rate of reaction. Some of them are described below:
i) Size of particle: Rate of chemical reaction increases with the increase in the surface area or decrease in size of reactant particles. For example, when calcium carbonate is reacted with dilute hydrochloric acid, calcium chloride and water are formed with liberation of carbondioxide gas as:

CaCO3 + 2HCl → CaCl2 + H2O + CO2

Rate of reaction can be monitored by the evolution of carbondioxide gas. Evolution of carbondioxide gas is more, when powdered CaCO3 is used rather than lump of CaCO3.

ii) Concentration: Rate of chemical reaction is directly proportional to concentration of the reactants. When concentration is increased, the frequency of collisions between reactant molecules increases. This increases the rate of reaction. In the above given reaction, the evolution of carbondioxide is more rapid when concentrated hydrochloric acid is used rather than dilute hydrochloric acid.

iii) Temperature: The rate of reaction also depends upon temperature. Rate of reaction increases with the increase in the temperature. When temperature is increased, the kinetic energy of reactant molecules increases and their collisions become more effective. It has been found that the rate of reaction increases by two to three times upon each 10oC rise in temperature.

iv) Catalyst: Catalyst increases the rate of reaction by providing alternate path for the reaction having lower activation energy. For example, iron acts as a catalyst during the manufacture of ammonia by Haber’s process. Similarly, the decomposition of potassium chlorate is catalysed by using manganese dioxide.

Average and Instantaneous Rate

Concentration of reactants decreases with time and hence rate of chemical reaction decreases with the propagation of reaction. The rate of reaction at certain interval of time is called average rate of reaction.
To determine average rate, a graph between concentration of reactant or product is plotted against time and concentrations at given time intervals are noted and average rate is determined.

Let us consider a reaction,

A → B

graph 12Average rate = – (A)2 – (A)1/t2 – t1 = + (B)2 – (B)1/t2 – t1
or, Average rate = –Δ(A)/Δt = +Δ(B)/Δt

Similarly, the rate of chemical reaction at a particular instant of time is called instantaneous rate of reaction. To determine the instantaneous rate, a graph between concentration of reactant or product is plotted against time. Then a perpendicular is drawn from the curve to the instant of time where the rate is to be determined. Finally, the slope of the tangent at the corresponding point on the curve gives the instantaneous rate.

34

Instantaneous rate = – (A)2 – (A)1/t2 – t1 = + (B)2 – (B)1/t2 – t1
or, Instantaneous rate = –dA/dt = +dB/dt
The average rate becomes instantaneous rate of reaction when Δt → 0.
∴ Instantaneous rate = Δt lim→ 0 Average rate
or, Instantaneous rate = Δt lim→ 0 – Δ A/Δ B
or, Instantaneous rate = –dA/dB