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Principle of potentiometer, when a constant current flows through a wire of uniform area of cross-section, the potential drop across any length of the wire is directly proportional to the length. 

 Let resistance of wire AB be R₁ and its length be ‘l’ then current drawn from driving cell – 

I = V/ (R + R₁) and hence

P.D. across the wire AB will be 

V_AB = IR₁ = (V eIθ)/ (R +R₁) α

Where ‘a’ is area of cross-section of wire AB 

∴ V_AB/ I = Ve/(R + R₁).α = constant = k

Where R increases, current and potential difference across wire AB will be

decreased and hence potential gradient ‘k’ will also be decreased. Thus the null point or balance point will shift to right (towards, B) side.

Joule is a unit of work.

Now by using the formula of work done 

W = F s(F = force and s = displacement)
= Mas    (a = acceleration)
= Msv/t   (v = velocity  and t = time)
=Ms s/t^​2 (as velocity is displacement /time)
W = M s²/t²

hence the above formula is in form of its fundamental units like mass, time and length and the dimension formula of joule = ML²T^-2

This can be made: 

(i) by changing the vibrating length of string or

(ii) by changing the tension on the string.

• Prohibition on the sale of arrack. 

• Provided a platform to discuss private issues of domestic violence.

Despite re-organisation of North-East in 1972, autonomy demand arose: 

• Assam communities like Bodos, Karbis and Dimosas demanded separate states. 

• They mobilised public opinion and popular movement and same area was claimed by more than one community. 

• Federal set up satisfied their autonomy i.e. Karbis and Dimosas were granted autonomy under district councils while Bodos were granted autonomous council.

On the issue of regional autonomy for Kashmir, the following positions are states as: 

1. Kashmiris were promised to make accession on reference of people after situation created by tribal invasion, becomes normal. But it has not been fulfilled, hence, it generated the demand for “Plebiscite”. 

2. Sometimes, it was felt that special federal status guaranteed by Article 370 has been eroded practically which led the demand for restoration of autonomy or “Greater State Autonomy”. 

3. It is felt that democracy, which is practised in rest of India has not been similarly institutionalised in Jammu and Kashmir. 

We prefer the first position because ‘Plebiscite’ provides better opportunity to people of J & K to protect and sustain their regional autonomy in a very democratic manner.

Almost all of us are fond of keeping pets. Specially, we have liking for dogs and puppies. It has become a status symbol to have a pet dog. In fact, keeping a dog as a pet is not only a status symbol but also it protects us from many dangers. I am also very fond of keeping pet specially a small dog or a puppy. So a few days ago, I bought a puppy of bull dog species. It was very cute puppy and I played a lot with it. It had been my routine that at the time of evening, I used to take my puppy for a walk. Yesterday, When I took the puppy for a walk suddenly he smelt some odd thing and ran towards the other side of the road. Even it broke the chain. The road was very busy. Uncounted vehicles were running from both the sides. The puppy came to the middle on the road then it had no way to cross the road. The traffic was very heavy and fast. The puppy was trying to have a safe passage to cross the road but he could not get any safe passage. I also ran after him. Suddenly, a speeding car came before him. The driver tried to stop the car with full strength. There was a loud sound of creaking the brakes. The tyres of the car rubbed on the road. The driver tried to save the puppy his best but he came under the car. He was severely wounded. I, at once, took him to the dog’s clinic. The veterinary doctor soon examined the puppy and started the treatment. The puppy was severely injured. He could not be saved. It was a cute and faithful puppy whose death pained me a lot.

My brother and I are the apples of our parents’ eyes. They always try to fulfil our needs and desires. We both are very fond of each other. We study together, we eat together and go to school together. We can’t do any work without the help of each other. But yesternight was an exception. I had a fight with my brother on a petty issue. I am very fond of eating ice cream. My father brought one cup of ice cream. I wanted to have the cup but soon my brother came. He also wanted to have the cup of ice cream. He tried to snatch the cup from my hand but I held the cup firmly so he could not do so. We had a fight on this issue. Being angry, my brother left home. I didn’t care as I had no effect because he had fought with me. But after some time, I began to feel alone as there was none to accompany me in my studies but to maintain my pride, I started my study even though I was getting bored. I began to miss my brother but he was not at home. As it became dark, I saw some shadows in the room wandering here and there. My heart started beating with a loud sound. After some time, there were some odd looking faces. There teeth were out of their mouths, I was terrified. I began to scream. Suddenly, I saw my parents and brother standing by my side. They were pushing my shoulder to wake me up. I was sweating. I told the whole dream to them. They began to laugh. I also began to laugh at the fight with my brother in my dream.

We know that the area of parallelogram 

= base x height

(a) Here, base = 20 cm and area = 246 cm²

\Area of parallelogram = base x height

⇒ 246 = 20 x height

⇒ height = 246/20

= 12.3 cm

(b) Here, height = 15 cm and area = 154.5 cm² 

\ Area of parallelogram = base x height

⇒ 154.5 = base x 15

⇒ base = 154.5/15

= 10.3 cm

(c) Here, height = 8.4 cm and area = 48.72 cm² 

\ Area of parallelogram = base x height

⇒ 48.72 = base x 8.4

⇒ base =48.72/8.4

= 5.8 cm

(d) Here, base = 15.6 cm and area = 16.38 cm² 

\Area of parallelogram = base x height

⇒ 16.38 = 15.6 x height

⇒ height = 16.38/15.6

= 1.05 cm

Thus, the missing values are:

In test-tube I.
Reason : Ag is less reactive than hydrogen. Hence, it cannot displace hydrogen from HCl acid.

Given,

V = 1.05 V 

I = 0.15 A 

V = IR

R = V/I = 1.05 V/ 0.15 A = 7 Ω

In test-tube I, II and IV 

Reason : It occured in test tube III because Al is more reactive than Cu, so it will displace Cu from CuSo₄

Fleming’s left-hand rule: Stretch the forefinger, middle finger and thumb of left hand in such a way that they are mutually perpendicular to each other. If the forefinger point in the direction of magnetic field, middle finger point in the direction of current then the thumb show the direction of force or motion on the current carrying conductor.

(a)  Function of armature: Enhances the power of the motor / induces motion.

(b)  Function of brushes: Helps easy transfer of charge between the coil and the external circuit.

(c)  Function of split rings: Reverses the direction of current after each half rotation of the coil so that the coil can keep rotating continuously.

(i) Armature: It is a rectangular iron core wrapped by the copper coil through which electricity passes and due to magnetic field it experiences a force and rotates.

(ii) Brushes: It conducts current between stationary wires and moving parts, most commonly in a rotating shaft.

(iii) Split Ring: It helps to reverse the direction of current in the circuit.

Armature - It is a rectangular coil that is placed in a uniform magnetic field. The main function of the armature is to rotate the shaft or axel to which it is attached. 

Brushes - They are attached (not fixed) to the split rings. The main work of these brushes is to transport current from the external circuit to the internal circuit.

Split rings - They are also known as commutators. The work of the split ring is to change the direction of current and which leads the rotation of the armature in the same direction.

Principle of working of electric motor: A coil carrying electric current placed in an external magnetic field experiences a force.

Stars are very distant and approximately point-sized sources. Pair of starlight changes continuously due to gradual changing of the refractive index of the layers of earth's atmosphere. Thus, the apparent position of the stars fluctuates and the amount of starlight entering the eye flickers giving the twinkling effect.

Early in the morning, the sun is near the horizon, sunlight reaches us after traveling a longer distance through thick layers of the atmosphere. Tirus, most of the blue light and shorter wavelength are scattered away by the particles in the atmosphere. The light that reaches us is of longer wavelengths giving a reddish appearance. This phenomenon will not be observed by an astronaut on the moon, because of the absence of atmosphere on the moon.

(i) Cornea: If refracts most of the light into eyes.

(ii) Iris: Gives colour to eyes, controls size of pupil.

(iii) Crystaline Lens: Focuses the image of the object on the retina.

(iv) Ciliary Muscles: Holds the eye lens and adjusts its focal length.

(i) The compound ‘X’ is sodium hydrogen-carbonate commonly known as baking soda.

(ii) The chemical formula of baking soda is NaHCO₃.

(iii) Action of heat : When sodium hydrogen-carbonate is heated during the cooking of food, it decomposes to give sodium carbonate with the evolution of carbon-dioxide gas.

2NaHCO₃ + Heat → Na₂CO₃ + CO₂ + H₂O

(i) volt-ampere 

Power = Voltage x Current.

(iv) Human faecal matter

Following are the list of four stakeholders which may help in the conservation of forests:

(a) Local people living in villages near forest area.

(b) Industrialists using the forest products.

(c) Wildlife and nature enthusiasts.

(d) Forest department of the government.

(iv) The industrialists

Passage question 

(a) the Central Asian countries want to maintain ties with both Russia and the West because they wanted to gain economic benefits from the both and for maintaining sovereignty.

(b) the new players that emerged in the international system after the disintegration of USSR -Azerbaijan, Kazakhstan, Russia, Turkmenistan, Ukraine, Kyrgyzstan , Georgia and Uzbekistan. 

(c) profound consequences of it on the world politics - the end of Cold War confrontations power relations in world politics changed and, the relative influence of ideas and institutions also. the US became the sole super power. the end of the Soviet bloc meant the emergence of many new countries. 

Neighbourhood Markets 

• Neighbourhood shops are convenient for the public as they are open daily and various products are available at different shops. Many shops are permanent and some are temporary like hawkers and vendors.
• The major advantages of these markets are that they are in the vicinity of our homes, there is an understanding between the buyer and the seller and we can get products on credit.

Shopping Complexes and Malls 

• Markets in urban areas are mostly shopping complexes or malls. Malls are multi-storeyed  air-conditioned buildings with shops at different levels.
• Mostly products available in the malls are branded, of high quality and are promoted by advertisement. These markets appeal mostly to the rich people and they are the ones that these brands cater to.

Properties of covalent compounds :

(i) These compounds contain directional covalent bonds which involve sharing of electrons.

(ii) They exhibit isomerism.

(iii) Covalent compounds have usually low melting and low boiling points.

(iv) Covalent compounds are usually in soluble in water but they are soluble in organic solvents.

(v) They have lower melting and boiling points.

Uses of Covalent compounds :

(i) Majority constituents in our body are covalent compounds.

(ii) Water is a covalent compound. We know its many uses.

(iii) Sugar, vinegar, cooking gas are all covalent compounds.

(iv) Important gases like CO₂, NH₃ are all covalent compounds.

(v) Almost everything on earth other than most simple in organic salts are covalent.

Production possibility curve is a curve which depicts all possible combinations of two goods which can be produced with given resources and technology in an economy. 

Following are the properties of a production possibility curve : 

1. Downward slope – Production possibility curve slopes downward from left to right. It is so because increase in production of one commodity is possible only by reducing the production of other. 

2. Concave to the origin – Production possibility curve is concave to the point of origin because of increasing marginal opportunity cost or marginal rate of transformation. 

3. Shift – Production possibility curve can shift to the right or to the left. It can shift to the left when resources decrease due to large scale natural calamities, war, fall in population etc. It can shift to the right where there is improvement of technology or increase in resources.

Following are two conditions of consumer’s equilibrium under indifference curve analysis: 

(i) MRS = Ratio of prices – Let the two goods be X and Y. The first condition for consumer’s equilibrium is that MRS = P_x/P_y. Now suppose MRS is greater than P_x/P_y. It means that the consumer is willing to pay more forXthan the price prevailing in the market. As a result, the consumer buys more of X. This leads to fall in MRS. MRS continues to fall till it becomes equal to the ratio of prices and the equilibrium is established. 

(ii) MRS continuously falls as more of a good is consumed – Unless MRS declines continuously as more and more of good X is consumed, it will not be equal to \(\frac{P_x}{p_y}\) and consumer will not be able to reach the equilibrium.

Consumer’s equilibrium will be at the point where he gets maximum satisfaction with the given money income. As such, a consumer will attempt to reach the highest indifference curve which is within his purchasing power shown by budget line. Hence, a consumer will be at equilibrium at the point when following two

1. MRS = Ratio of prices – Let the two goods be X and Y. The first condition for consumer’s equilibrium is that MRS – Px/Pv. Now suppose MRS is greater than Px/Py. It means that the consumer is willing to pay more for X than the price prevailing in the market. As a result, the consumer buys more of X. This leads to fall in MRS. MRS continues to fall till it becomes equal to the ratio of prices and the equilibrium is established. 

2. MRS continuously falls – Unless MRS continuously falls, die equilibrium cannot be established. Adjacent diagram shows the equilibrium of a consumer. A consumer will be at equilibrium at E because he gets maximum satisfaction from his given money income. He will not like to shift to any point left to E because the level of satisfaction is lower. He will like to move to right of E but his money income is not sufficient to achieve it.

Downward slope of the indifference curve to the right implies that a consumer cannot simultaneously have more of both the goods. An increase in the quantity of one goods is associated with the decrease in the quantity of the other goods. This is in accordance with the assumption of monotonic preferences.

Na₂SO₄(aq) + BaCl₂(aq)→BaSO₄(s) + 2NaCl(aq)

A white precipitate of barirrm sulphate insoluble in water is observed. It is a double displacement reaction

White precipitate is observed

Na₂SO₄(aq) + BaCl₂(aq) ----> BaSO₄(s) + 2NaCl(aq)

Double displacement reaction

Elliptical shape pore is stoma/stomata. 

Kidney shape is guard cells.

(i) No change/ remains colourless 

(ii) No change 

(iii)Turns pink/orange 

(iv) Evolution of colourless gas

No reaction with distilled water. Chemical reaction occurs with solution of NaHCO₃
Two Observations:
(i) Evolution of a colourless, odourless gas.
(ii) The gas is evolved with brisk effervescence

(i) Acetic acid will remain colourless in phenolphthalein. 22. 

(ii) Acetic acid will dissolve in distilled water forming a clear solution. 

(iii) Universal indicator gives orange colour with acetic acid. 

(iv) Sodium hydrogencarbonate will give brisk effervescence due to the formation of CO₂ gas.

Set I will have more length of foam because it consists of soft water. 

Set II will form less foam because it consists of hard water due to the presence of CaSO₄.

(i) The set-up should be airtight. 

(ii) Germinating seeds (living) should be used.

(i) The set up should be airtight. 

(ii) Germinating seeds (living) should be used.

To determine the genotype of F₂ generation.

When migration of a section of population to another place and population occurs, gene frequencies change in the original as well as in the new population. New genes/alleles are added to the new population and these are lost from the old population. Sometimes the change in allele frequency is so different in the new sample of population that they become a different species. The original drifted population becomes founders and the effect is called founder effect.

Hardy-Weinberg equation is p² + 2pq + q² = 1. This means that the sum total of all the allelic frequencies is 1. In a diploid, p² means that the probability an allele AA with a frequency of p appear on both the chromosomes of a diploid individual will be p2 . Similarly of allele aa is q² , and of Aa is 2pq.

Absence of one X chromosome leads to XO abnormality. These are sterile female with rudimentary ovaries. They have shield-shaped thorax, webbed neck, poor development of breasts, short stature, small uterus and puffy fingers.

Since the information given in the question is inaccurate, full marks are to be awarded to every candidate.

(a) Testis : To produce male gametes/ sperms or male hormones/ testosterone. 

(b) Scrotum : To provide optimal temperature to testis for the formation of sperm. 

(c) Vas deferens : To deliver the sperms to the urinary bladder. 

(d) Prostate glands : To secrete the fluid which provides nutrition and medium for transport of sperms.

Functions of the nervous system : 

(i) Collects information from the surroundings. 

(ii) Controls and co-ordinates the movement of muscles. 

(iii) Helps to recognise smell, taste, vision, hearing etc. with the help of sense organs.