A convex lens made up of glass (μ = 1.5) has 20 cm focal length in air (μ = 1). Then its focal length in water (μ = 1.33) will be :
The critical angle of light going from denser medium to rarer medium is θ. If the speed of light in denser medium is v, then speed of light in rarer medium is
For a glass prism of refractive index the angle of minimum deviation is equal to the angle of prism, then angle of prism is
There is a small object at centre C of a solid glass sphere of refractive index μ. When seen from outside, the dot will appear to be located
A lens behaves as a converging lens in air and a diverging lens in water. The refractive index of the material is
A quartz slab is placed inside glycerine as shown in the figure. The shift of object observed by observer on left side is :
The largest distance of the image of a real object from a convex mirror of focal length 20 cm can be
As x0 increases, v increases
⇒ vmax occurs when x0 = infinity
⇒ vmax = 20 cm
A hypermetropic person can see the objects beyond 1 m from his eyes. What should be the power of spectacles we should use so that his least distance of clear vision becomes 25 cm
A simple microscope has a focal length of 2.5 cm. Maximum angular magnification of it will be (Given that least distance of clear vision = D = 25 cm)
A normal human eye can see from 25 cm to infinity. If the distance between eye lens and retina is 2 cm, then which of the following is correct?
In a compound microscope, the intermediate image is
Stopping potential in photoelectric experiment for a given metal surface
When a transistor is used in common emitter mode as an amplifier
The output of a NAND gate is 0, when
Q. The resistance of a germanium junction diode whose V−I is shown in the figure is (Vk=0.3V)
In the circuit shown, I1 and I2 are respectively
i = 10/2
= i2, i1 = 0
Input applied to the following circuit will produce which of the following output signal, assuming R1 = R2 and diode is ideal.
If Vin = Positive, then diode will be reverse biased, hence no output.
If Vin = Negative, then diode will be forward biased, hence potential difference across R2 will be 2.5V.
If the ratio of amplitudes of two coherent sources producing an interference pattern is 3 : 4, then ratio of intensities at maxima and minima is
The ionization potential of hydrogen atom is − 13.6 V. Photons of energy 12.75 eV are made to incident on sample of H atoms at ground state. How many spectral lines are expected in emitted radiation?
E1 = -13.6, E2 = -3.4, E3 =- 1.5, E4 = -0.85; So electron can go upto 4th orbit from ground state. Total no. of ways by which this is possible = 6.
Electromagnetic radiations of intensity I is incident normally on a perfectly reflecting surface. If speed of light is C, then radiation pressure exerted on the surface is
Let no. of photons falling per second per unit area = n
So, I = nhf
Pressure = Force/Area = 2n(h/λ) = 2nhf/c = 2I/c
A beam of unpolarised light travelling in air is reflected from a solid surface at an angle of reflection 60°. If the reflected light is plane polarized, then refractive index of the solid is
Using brewster’s law, μ=tan (i) = tan 60°
de-Brogile wavelength associated with a proton accelerated from rest by 10 kV is λ. The de-Brogile wavelength associated with a 10 keV neutron is
where k is kinetic energy of particle. According to given data, kinetic energy of proton is 10keV which is same as that of neutron. Masses are also same.
Momentum of an alpha particle emitted from a stationary nucleus is. Momentum of the daughter nucleus should be
Apply momentum conservation principle.
Percentage of radioactive sample decayed in 2 half lives is
After 2 half lives, N = N0/4, but decayed nuclei = 3 N0/4 = 75%
In a Young’s double-slit experiment, the intensity at a bright fringe is I0. If one of the slits is now covered, the intensity at any point on the screen will be
Ibright = 4Islit
In a Young’s double-slit experiment, the central bright fringe can be identified
In a Young’s double-slit experiment, if the slits are of unequal width,
will not cancel each other if widths are unequal.
In a Young’s double-slit experiment, the fringe width is β. If the entire arrangement is now placed inside a liquid of refractive index μ, the fringe width will become
In a Young’s double-slit experiment, let S1 and S2 be the two slits and C be the centre of the screen. If ∠S1CS2 = θ and λ is the wavelength, the fringe width will be
Because, d/D = θ & fringe width = Dλ/d
The penetrating powers of α, β and γ radiations, in decreasing order, are
In a radioactive series, changes to through n1 α-decay processes and n2 β-decay processes.
4 n1 = 238 – 206 = 32, so n1 = 8
2 n1 – n2 =92 – 82 = 10, so n2 = 6
Let u denote one atomic mass unit. One atom of an element of mass number A has mass exactly equal to A u
Two nucleons are at a separation of 1 fm. The net force between them is F1 if both are neutrons, F2 if both are protons, and F3 if one is a proton and the other is a neutron.
Nuclear forces will be same all three cases but total force F2 will be smaller because of electrostatic repulsion between two protons.
A sample of radioactive material has mass m, decay constant λ, and molecular weight M. Avogadro number = NA. The initial activity of the sample is
Activity = λ X No. of nuclei = λ X Moles X NA = λm NA/M
An orbital electron in the ground state of hydrogen has an angular momentum L1, and an orbital electron in the first orbit in the ground state of lithium atom has an angular momentum L2.
Bohr’s postulate L = nh/2π, L does not depend on atomic number.
When white light (violet to red) is passed through hydrogen gas at room temperature, absorption lines will be observed in the
According to bohr's model, the velocity of an electron orbiting in the nth orbit of hydrogen like atom is proportional to nx where x is
A free neutron decays into a proton, an electron and :
If the potential difference applied across a Coolidge tube is increased, then
Potential difference only affects continuous X-Rays and not characteristic X- Rays.
The half-life of 131I is 8 days. Given a sample of 131I at time t = 0, we can assert that
A : Two coherent point sources of light having nonzero phase difference are seperated by small distance. Then on the perpendicular bisector of line segment joining both the point sources, constructive interference cannot be obtained.
R : For two waves from coherent point sources to interfere constructively at a point, their phase difference at that point must be nπ (where n is an integer).
A : A point object moves near the principal axis of a fixed spherical mirror along a straight line. Then the image formed by the spherical mirror also moves along a straight line.
R : For an incident ray on a fixed spherical mirror there is a fixed reflected ray. If a point object moves along this incident ray, its image will always lie on the given reflected ray.
A : In Bohr’s atomic model, speed of electron in an orbit is inversely proportional to the radius of the orbit of given principal quantum number.
R : Bohr’s second postulate state that angular momentum of electron in nth
A : In N-type silicon, electrons are the majority carriers.
R : N-type semiconductors are doped with trivalent impurities.
A : In spontaneous fission, the energy is always released.
R : S pontaneous fission occurs to increase the binding energy per nucleon.
Nylon-66 is a polyamide of
Arrange the following compounds in the order of leaving group ability
Weaker the base, better is the leaving group. Hence, basicities decrease in the order
Therefore, the order of leaving group ability decreases in the reverse order (IV) > (III) > (I) > (II).
An SN2 reaction at asymmetric carbon of a compound always gives
In SN2 reaction, inversion of configuration occurs. Since the reactant and the product are not enantiomers, the sign of optical rotation may or may not change, hence single stereoisomer is obtained.
Replacement of ‘Cl’ of chlorobenzene to give phenol requires drastic conditions but chlorine of 2,4-dinitrochloro benzene is readily replaced because
NO2 group withdraws electrons from ortho and para positions, hence activates Cl towards nucleophilic substitution reactions
Chlorination of toluene in the presence of light and heat followed by treatment with aqueous NaOH gives
Neopentyl alcohol on treatment with HBr gives
Which of the following derivatives of benzene would undergo hydrolysis most readily with aq. KOH?
– NO2 group increases the reactivity in nucleophilic substitution on benzene ring due to –R and –I effect.
On warming with I2 and aqueous NaOH, iodoform and sodium succinate are formed. The formula of the compound should be
CH3COCH2CH2COOH CHI3 + HOOCCH2CH2COOH and
CH3COCH2CH2COOH3 2CHI3 + HOOCCH2CH2COOH
Which of the following statement is correct?
Cl is o, p-directing and hence on further chlorination will give a mixture of o- and p-dichlorobenzene.
An organic compound (A) (MF C4H10O) upon dehydrogenation gives a compound (B) which forms phenyl hydrazone with phenylhydrazine and both the compounds (A) and (B) respond to iodoform test. Hence, the compound (A) is
Phenol does not react with NaHCO3 because
Carbonic acid is stronger than phenol.
HBr reacts fastest with
As more stable carbonium ion is formed.
The strongest acid among the following aromatic compounds is
Nitro is strongly electron withdrawing group. At ortho position intramolecular hydrogen bond reduces the acidic strength.
Glycerol on heating with concentration H2SO4 gives
The A is :
The reaction is an esterification:
An amide (A) C3H7NO on hydrolysis gives an amine (B) and an acid (C). B gives carbylamines reaction where as C reduces Tollen’s reagent. (A) is
and acid (C) reduces. Tollens reagent, (C) is a formic acid. (B) gives carbylamines reaction therefore B is a primary amine with two carbon atoms. (B) is ethyl amine.
Which of the following is an example of basic dye?
The major product obtained when Br2/Fe is reacted with
NH group is an activating group and determines the position of incoming electrophile. The NH group is O, Pdirecting but orthoposition is blocked So Br comes at para w.r.t. to NH.
Identify ‘Y’ in
In a Cannizzaro’s reaction, the intermediate that will be the best hydride donor is
The appropriate reagent for the transformation is
Both Zn(Hg)/HCl and NH2–NH2/OH– can reduce COCH3 group to CH2–CH3 but HCl will also bring about replacement of OH group by Cl. Therefore, the most appropriate reagent is NH2 – NH2/OH–.
Identify the product (c) in the series
CH3CH2NH2 + HO - N = O → CH3 - CH2OH + N2 + H2O
In the reaction CH3 - CH = CH - CHO CH3 - CH = CH - COOH, the oxidizing agent can be
CH3 - CH = CH - CHO CH3 - CH = CH - COOH,
Benedict solution (solution of CuSO4, sodium carbonate and sodium citrate) is specific for oxidation of aldehydes.
Which of the following statements about benzaldehyde is true?
Benzaldehyde reduces Tollen’s reagent and undergoes Cannizzaro reaction. However, it forms an addition compound with NaHSO3 but does not undergo aldol condensation.
Benzophenone (C6H5COC6H5) does not react with
Due to the electron donating nature of the two phenyl groups, the +ve charge on the C – atom of the CO group is diminished to such as extent that weak nucleophiles such as HCN, NaHSO3 and CH3OH do not react with benzophenone. Therefore, only NH2OH reacts.
C7H7Cl on reaction with KMnO4 followed by the action of soda lime gives only chlorobenzene. The compound C7H7Cl is
The correct order of increasing boiling point of the following compound is
II < III < IV due to higher mol. wt. and (I) has got highest boiling point because of the presence of H- bonding.
When propanoic acid is treated with aqueous sodium bicarbonate, CO2 is liberated. The ‘C’ of CO2 comes from
Thus, carbon atom of CO2 comes from bicarbonate
Which of the following acids has the smallest dissociation constant?
Br–CH2–CH2–COOH is the weakest acid since Br has lower –I effect as compared to F and is also far away from –CO2H group.
The molecular weight of benzoic acid in benzene as determined by depression in freezing point method corresponds to
In benzene, benzoic acid undergoes dimerisation and hence the molecular weight of benzoic acid as determined by depression in freezing point method is twice the actual molecular weight.
R–CH2–CH2–OH can be converted into R–CH2–CH2–COOH. The correct sequence of reagents is
Among the following bromides given below, the order of their reactivity in the SN1 reaction is
The product (B) formed in the above reaction is
Benzoylchlroide is prepared from benzoic acid by
Which of the following statements are true about HCOOH?
It is stronger acid than CH3COOH and it reduces tollen’s reagent.
The end product of the following reaction would be
The order of reactivity of the following esters towards hydrolysis is
Which of the following is not a chromophore?
Chromophore is colour bearing group
In the following questions a statement of Assertion (A) is followed by a statement of Reason (R).
A : Gabriel-phthalimide synthesis is used to prepare only primary amines.
R : The reaction involves neuleophilic substitution reaction.
A : Hinsberg test is used to distinguish 1°, 2° and 3° amines.
R : H insberg test is based on solubility of sulfonates in KOH.
A : 6-oxoheptanal on treatment with dilute NaOH gives 1-acetylcyclopentene.
R : In intramolecular aldol condensation, the Carbanion should be formed from α-carbon of ketone and it attacks on aldehydic carbon to form finally α-β unsaturated carbonyl compound.
A : The order of reactivity of different haloalkanes towards β-elimination is 3° > 2° > 1°.
R : 3° alkyl halides yield more substituted alkene, which being more stable are formed at faster rate.
A : Reimer-Tiemann reaction is an example of electrophilic substitution where the electrophile is dichloromethylene.
R : Dichloromethylene is electron deficient and is formed by the reaction between chloroform and alkali.
Match the following list of bioactive substances and their roles :
Choose the correct match:
What would happen if oxygen availability to activated sludge flocs is reduced ?
Match the items in Column ‘A’ and Column ‘B’ and choose correct answer :
The correct answer is :
Mycorrhiza does not help the host plant in:
Mycorrhiza helps the host plant in enhancing its phosphorus uptake capacity, in increasing its tolerance to drought. Mycorrhiza produces some chemicals which resist the pathogen like Fusarium.
So, the correct option is 'increasing its resistance to insects'
Biological Pest Control methods are more preferably used because-
Stage of temporary suspension of development under unfavorable condition is known as-
Mark the correct statement w.r.t. to declining population-
(i) The graph is urn shaped
(ii) Such population shows positive growth
(iii) It has a small no of pre-reproductive and reproductive population
(iv) It represents young population
The interaction between two living organism of different species where one remains unaffected and the other get harmed is-
The VerhulstPaul logistic growth is expressed as what does 'r' represents-
A. Experimental removal of Pisaster resulted in extinction of more than ten species of invertebrates in that area.
B. Cactus population in Australia decreased tremendously by introduction of Moths.
C. Predators help to maintain species diversity.
Find the incorrect statement/s-
In India we have many deserts, forests, hill areas, rivers, lakes and ponds. This statement indicates about-
David Tillmann’s experiments show that-
If parasitism is an examples of +ve, – ve interaction then competition is an example of-
The magnitude of 'r' for human population in India, during 1981 was-
The total changes taking place in a completely barren area are collectivity referred as-
Study the organisms- Man, Lion, Birds, Fishes, Wolf, Zooplanktons, Grasshopper, Cow, Phytoplanktons, Grasses, Trees.
Q. How many organisms present in the above box are secondary consumer?
The correct option is Option B.
The secondary consumers are carnivores that are dependent on primary consumers.
Lions will depend on herbivores.
Wolves depend on herbivores.
Birds depend on insects.
Fishes depend on zooplanktons.
Hence, there are four secondary consumers.
The rate of decomposition of detritus is accelerated-
Which one of the following shows pyramid of numbers in a single tree ecosystem?
Biomass present at a trophic level in an area at any time is called-
Which one of the following has the lowest number of species in nature-
Montreal Protocol was passed in-
Match the following
Government of India has introduced a concept to work closely with local communities for protection and management of forest. It is known as.
'Ecosan' toilets are working in many areas of
A. CFC is the most effective greenhouse gases
B. CFC is the most damaging to ozone layer
C. UV - B causes show blindness
D. Ozone is both friend and foe as it is considered good in troposphere and bad in stratosphere
How many of the above statement are correct
Which of the following statement is incorrect?
How many of the following statements are correct?
1. Primary productivity of an ecosystem depends upon plant species of that area and not on environmental factors
2. During decomposition oxygen is required; the rate is controlled by chemical composition of detritus and climatic factors
3. In aquatic ecosystem GFC is major conduit of energy flow, whereas in terrestrial ecosystem it is DFC.
4. In most ecosystems, all the pyramids are upright.
Loss of biodiversity in a region might lead to all except-
Out of the following six statements how many of them are correct?
1. Electrostatic precipitator can remove more than 99% of particulate matter
2. According to CPCB particulate size 2.5 or less in diameter are most harmful for human health
3. Catalytic converter reduces emission of poisonous gas
4. Amount of biodegradable inorganic matter in sewage water is estimated by measuring BOD
5. Biomagnification is due to the metabolisation of toxic substance by living organisms
6. Eutrophication is natural aging of lake by nutrient enrichment of its water
Read the following four statements (1 – 4), find out certain mistakes in two of them.
(a) In our stomach lactic acid bacteria play beneficial role by checking growth of disease causing microbes.
(b) Lactic acid bacteria produce acid that coagulates and completely digests the milk protein.
(c) Lactic acid bacteria improves the nutritional quality by increasing the amount of Riboflavin
(d) Lactic acid bacteria require suitable temperature for their multiplication.
Which of the two statements having mistakes?
A person who is working as a disc jockey (DJ) might suffer from;
Which one of the following pairs is wrongly matched remaining three are correct.
Ecosystem requires constant supply of energy to synthesise the molecules they require for;
In hydrarch succession pioneer is phytoplankton and climax is forest (mesic). Given below is name of seral stages, arrange them in accordance with their appearance.
A. Submerged free floating plants
B. Reed – swamp stage
C. Marsh meadow stage
D. Submerged plant stage
E. Scrub stage
What do you mean by bio-prospecting?
In high yielding hybrid crop varieties,to exploit hybrid vigour, the farmers need to purchase fresh hybrid seed every year because :-
Choose the correct for decomposition:-
For animal breeding-
In the following questions a statement of Assertion (A) is followed by a statement of Reason (R).
A: The phase of agriculture between 1960 - 1970 is often called green revolution.
R: There was development of several dwarf varieties of wheat and rice during this phase.
A: Bt cotton is a transgenic crop plant.
R: It does not allow the weeds to grow nearly.
A: Temporary movement of organism from stressful area to more favorable area in called migration.
R: It has no impact on population of birds and fishes.
A: Herbicide resistance crop plants are safer for human use.
R: They do not accumulate the toxic herbicides in fruits and vegetables.
A: Green muffler are trees planted along the river side.
R: They are able to absorb sound vibration completely.
It is estimated that more than 70 % of the world’s livestock population is in India and China. But the contribution to the farm produce worldwide is only 25 %. Why?
Poultry is the class of domesticated fowl used for food or for their eggs. These include
Breeding of animals is an important aspect of animal husbandry. Breeding aims at
Mark the incorrect statement -
Male bull is considered to be superior only if
Continued inbreeding reduces fertility and productivity. This is called
Read the following statements carefully and mark the correct option-
(1) Inbreeding increases homozygosity
(2) Inbreeding hides harmful recessive genes that are not eliminated by selection
(3) It helps in accumulation of inferior genes and elimination of useful genes.
(4) Inbreeding is necessary if we want to evolve a pure-line in any animal.
How is fertility and yield restored after inbreeding depression?
Which method would you employ for animals that are below average in productivity, milk production, and growth rate?
Read the following statements and mark the correct answer
Mark the correct statement w.r.t. MOET-
Arrange in order from the beginning of the event -
(1) The fertilized eggs at 8-32 cell stage are recovered non-surgically and transferred to surrogate mothers.
(2) Cow is administered hormones, with FSH-like activity
(3) The animal is mated with an elite bull or artificially inseminated
(4) They produce 6-8 eggs
Mark the correct statement w.r.t. bee keeping-
Which of the following has proved helpful in preserving pollen as fossils?
Sporopollenin has proved helpful in preserving pollen as fossils. The covering of pollen grain, sporoderm is consist of two layers, viz., exine and intine. Exine is made of a highly resistant fatty substance called sporopollenin.
It could not be degraded by any enzyme. It is not affected by high temperature, strong acid or strong alkali. Thus, it keeps the pollen grains well-preserved as fossils.
Pollenkitt is a yellowish, viscous, sticky and oily layer that covers exine of some insect-pollinated pollen grains. Intine of pollen grains is made up of pectin and cellulose.
Mark the odd one out w.r.t to fishes.
Pomfrets are marine fishes.
Observe the diagram carefully and mark the correct explanation for the rop in the figure
Eco RI is the restriction enzyme in which R stands for -
Which of the following is incorrect statement for restriction enzymes?
Which of the following statement is incorrect with respect to polymerase chain reaction?
The Ti-plasmid is often used for making transgenic plants. This plasmid is found in
Agrobacterium has Ti Plasmid .
Which of the following is a disarmed pathogen vector?
The disarmed pathogen vectors are used because, the vectors have been genetically modified so that the virulent and the pathogen properties are not there. In other words, a more efficient process of transfering the DNA in to the host without any risk of infection or mistakes.
A modified Ti or Ri plasmid can be used. The plasmid is 'disarmed' by deletion of the tumor inducing genes; the only essential parts of the T-DNA are its two small (25 base pair) border repeats, at least one of which is needed for plant transformation.
The genetic defect-Adenosine Deaminase (ADA) deficiency may be cured permanently by
The illustration below shows maturation of pro-insulin into insulin. Identify X
Mature insulin lacks C peptide.
Approximately how many restriction enzymes have been isolated from the different (over 230) strains of bacteria?
During gel electrophoresis for separation of DNA fragment
After electrophoresis, the separated DNA fragments can be visualized in ethidium bromide gel exposed to UV light. These DNA fragments appear as ……. colored bands
After completing the transformation experiments involving the coding sequence of enzyme α-galactosidase, the recombinant colonies should
Which of the following method can be used for making the bacterial cell ‘competent’?
RNA interference technique involves -
The cutting of DNA by restriction endonuclease results in the fragments of DNA. These fragments are generally separated by a technique known as