An alternating current is given by the equation i = i1 cos ωt + i2 sin ωt . The rms current is given by
The number of electrons emitted by a surface exposed to light is directly propotional to
4 eV is the energy of the incident photon and the work function in 2 eV. What is the stopping potential
A parallel plate capacitor is filled by copper plate of thickness b. The new capacity will be
A heavy steel ball of mass greater than 1Kg moving with a speed of 2ms-1 collides head on with a stationary ping pong ball of mass less than 0.1g. The collision is elastic. After the collision the ping pong ball moves approximately with a speed
When the speed of electrons increases, then the value of its specific charge
An energy source will supply a constant current into the load, if its internal resistance is
If a radiation of energy E falls normally on a perfectly reflecting surface, then the momentum transferred to the surface is
Electron volt is a unit of
A 100 mH coil carries a current of 1 ampere. Energy stored in it is
In a D.C. motor induced e.m.f will be maximum
In an ideal parallel LC circuit, the capacitor is charged by connecting it to a.c.d. source, which is then disconnected. The current in the circuit
The idea of displacement current was introduced by
The ratio of charge to potential of a capacitor is known as its
In an oscillating LC circuit the maximum charge on the capacitor is Q. The charge on the capacitor when the energy is stored equally between the electric and magnetic fields is
A paralel plate capacitor of capacity 100 μ F is charged by a battery of 50 volts. The battery ramins connected and if the plates of the capacitor are separated so that the distance between them become double the original distance, the additional energy given by the battery to the capacitor in joules is
The enegy stored in wound watch spring is
Two masses of 1 gm and 4 gm are moving with equal kinetic energies. The ratio of the magnitudes of their linear momentum is
The temperature of a body falls from 50ºC to 40ºC in 10 minutes. If the temperature of the surroundings is 20ºC Then temperature of the body after another 10 minutes will be
The resistance of two bulbs of the same voltage are in the ratio 1:2. On connecting them in parallel the power consumption will be in the ratio
A magnet of magnetic moment M is cut into two equal parts. The two parts are placed perpendicular to each other so that their north poles touch each other. The resultant magnetic moment is
Magnetic moment of each part = m/2
Resultant magnetic moment of perpendicular magnets
At the magnetic poles of the earth, a compass needle will be
Two wires of the same material and length, but diameters in the ratio 1 : 2 are stretched by the same force. The elastic potential energy stored per unit volume for the two wires when stretched, will be in the ratio of
A person sitting in an open car moving at constant velocity throws a ball vertically up into air. The ball falls
Radioactive sodium in the form of sodium chloride, is used to detect
A particle executes simple harmonic motion with an angular velocity and maximum acceleration of 3.5 rad/sec and 7.5 m/s2 respectively. Amplitude of the oscillation is
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): The roaring of a lion is of low pitch while the buzzing of a mosquito is of high pitch.
Reason(R): Pitch is that characteristic of sound which enables us to distinguish between a shrill sound and a grave sound.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): A galvonometer is said to be sensitive if a small current through it produces a small deflection.
Reason(R): Current sensitivity = (symbols have their usual meaning).
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): The value of T such that v(t + T) = v(t) in a S.H.M. is 2π/ω.
Reason(R): A S.H.M. repeats at regular intervals called time period.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): If ℇ0 and μ0 respectively the electric permittivity and magnetic permeability of free space, and E and υ the corresponding quantities in a medium then refreactive index,
Reason(R): Speed of light in free space
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): A force is required to put a stationary body in motion or stop a moving body and some external agency is needed to provide this force. The external agency may or may not be in contact with the body.
Reason(R): The external agency can provide force on a body even from a distance.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Neutrons can be accelerated by cyclotron.
Reason(R): Neutrons are too heavy.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): For a dipole, the field and potential falls off as
Reason(R): For a quadrupole, the field and potential varies as
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Mass of mesons is added to the mass of the nucleus.
Reason(R): The rest mass of π-meson added is little more than the rest mass of electron.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Nuclei having number about 60 are most stable.
Reason(R): When two or more light nuclei are combined into a heavier nucleus, then the binding energy per nucleon will increase.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Base of a mountain does experience a shearing stress-resulting in a flow.
Reason(R): Non-uniform compression due to the rocks at the top is responsible for the shearing stress.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): If the Earth suddenly contracts to 1 / nth of its present size without any change in its mass. The duration of the new day will be 24 / n hrs.
Reason(R): The time period revolution of earth is not directly proportional to radius of the earth.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): The combination Y = sin ωt + cos2 ωt is not a simple harmonic function even though it is periodic.
Reason(R): All periodic functions satisfy the relation
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): The magnetic field at the ends of a long solenoid is half of that at the centre.
Reason(R): The magnetic field within the solenoid is uniform and parallel to the axis of the solenoid.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): When charges are shared between two bodies, there occurs loss of energy.
Reason(R): In case of sharing of charges, conservation of energy fails.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): The quartz fibres in moving coil galvanometer are silvered
Reason(R): Silvered surface reflects maximum light.
The quartz fibres are silvered to make them conducting
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): When a motor car is started, its head lights become slightly dim.
Reason(R): When the motor car is started , resistance in the path of current increases .
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): The expression (where i is current E the emf,and (R + r) total resistance) express the law of conservation of energy for the electrical circuit).
Reason(R): When no current is being drawn from the cell then the potential difference across the plates of the cell equals the emf of the cell.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): The speed of sound is more in gases compared to liquids .
Reason(R): (Symbols have their usual meaning)
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): When the resistance connected series with a cell is exactly is halved, the current is exactly doubled.
Reason(R): Reason (is current, E is emf, R the external resistance r the internal resistance).
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): If half of an isotope of lead is 26.8 minutes, then when this isotope of lead forms some compound by chemical combination, its half life is reduced.
Reason(R): Half life
An electric motor creates a tension of 4500 newton in a hoisting cable and reels it in at the rate of 2 m/sec. What is the power of electric motor
When a body is thrown with a velocity u making an angle θ with the horizontal plane, the maximum distance covered by it in horizontal direction is
Ultra-violet rays are detected by
Refractive index
To minimise spherical aberration two lenses of focal lengths f1 and f2 are placed with a distance separation equal to
In a semiconductor crystal if current flows due to breakage of crystal bonds, then the semiconductor is called
A N-type semiconductor is
For electroplating a spoon,it is placed in the voltameter at
Tesla is the unit of
When distance between source of light and observer decreases, then the apparent frequency of light
The dimensions of surface tension are
A wave front travels
Bright colours exihibited by spider's web exposed to sun light are due to
Under the action of a force, a 2 kg body moves such that its position x as a function of time is given by x = t3/3, where x is in meters and t is in sec. The work done by the force in the first two seconds is
Ethyl alcohol exhibits acidic character on reacting it with
The hydrogen phosphate of certain metal has formula MHPO₄. The formula of metal chloride would be
A compound that easily undergoes bromination is
In Friedel's-Craft alkylation, toluene is formed by
The most reactive among the following towards sulphonation is
Freon is used as a
In graphite, the electrons are
Homolytic fission of C — C bond in ethane gives an intermediate in which carbon is
Homolytic fission of C — C bond gives free radicals in which carbon is sp2 hybridised.
The hybrid states of carbon in diamond, graphite and acetylene are respectively
For a zero order reaction A → P, t1/2 is (k is rate constant)
The reason for almost doubling the rate of reaction on increasing the temperature of the reaction system by 10ºC is
In which one the following reactions does the heat change represents the heat of formation of water
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): The order of a reaction may be negative.
Reason(R): In some cases, the rate of reaction decreases as the concentration of the reactant increases .
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Glass and cement are man made silicates.
Reason(R): Glass is a speudo solid.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): In calcination, the ore is heated with calcium.
Reason(R): Calcination is done to recover calcium metal.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Absorption spectrum consists of some bright lines separated by dark lines.
Reason(R): Emission spectrum consists of dark lines.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Potassium and cesium are used in photoelectric cells.
Reason(R): They emit electron on exposure to light.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Principal, Azimuthal and Magnetic quantum numbers could be derives frm the Schrodinger wave equation .
Reason(R): Spin quantum number has value of
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): [Al(NH3)6]3+ does not exist in aqueous solution.
Reason(R): NH3 is a neutral ligand.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Methanol is stronger acid than water.
Reason(R): Among monohydric aliphatic alcohols methanol is the strongest acid.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Anisole undergoes electrophilic substitution at ortho and para positions.
Reason(R): Anisole is less reactive than phenol towards electrophilic substitution reactions.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Tetracycline is a will known broad spectrum antibiotic.
Reason(R): It can kill large number of bacteria of gram positive as well as gram negative stains.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Melting point of calcium halides decreases in the order CaI₂>CaBr₂>CaCl₂.
Reason(R): Smaller ions have lesser polarisability and thus their compounds are more ionic.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): The unit of constant b is L mol⁻1.
Reason(R): The constant b is characteristic of a gas.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Cycloheptatrienyl cationshows unusual stability.
Reason(R): All unsaturated compounds having (4n + 2)π electrons show unusual stability.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Si and Ge are semi-metals or metalloids.
Reason(R): They exhibit properties of metal and non-metal both.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Mountaineers have to carry oxygen cylinders to avoid altitude sickness.
Reason (R): At altitudes as atmospheric pressure is low, air is less dense and less oxygen is available for breathing. this is explained by boyle's law.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): CH3COOH but not HCOOH can be halogenated in presence of red P and Cl2.
Reason(R): Both formic acid and CH3COOH are highly soluble in water.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Hydrogen resembles alkali metals.
Reason(R): It is a good reducing agent like other alkali metals.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Sulphur cross links are present in vulcanised ruber.
Reason(R): Vulcanisation is a free radical initated chain reaction.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): For the process to be spontaneous ∆G as well as ∆S has to be less than zero.
Reason(R): For spontaneous change, ∆STotal > 0.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the Statements carefully and mark the correct answer-
Assertion(A): Maximum number of electrons in a shell can be 2n2.
Reason(R): Maximum number of electrons in a subshell can be 2,6,10,14 in s,p,d,f respectively.
Four moles of electrons were transferred from anode to cathode in an experiment on electrolysis of water. The total volume of the two gases (dry and at STP) produced will be apporximately (in litres)
The standard reduction potentials of Zn2+ | Zn , Cu2+ | Cu and Ag+ | Ag are respectively -0.76, 0.34 and 0.8 V. The following cells were constructed
a) Zn | Zn2+ ∥ Cu2+ | Cu
b) Zn | Zn2+ ∥ Ag+ | Ag
c) Cu | Cu2+ ∥ Ag+ | Ag
What is the correct order of E0 cell of these cells?
When the temperature of an ideal gas is increased 27ºC to 927ºC, then its kinetic energy will be
Which one of the following reactions is not associated with the Solvay process of manufacture of sodium carbonate?
An aqueous solution of sodium carbonate is alkaline because sodium carbonate is a salt of
Which of the following has the highest conductivity?
Which has the highest molar heat of vaporization?
The element having atomic no. 56 belongs to
The ionic product of water will increase if
The product of the concentration of hydronium ions and hydroxyl ion in pure water or in any acidic or basic solution is constant at a particular temperature.
It is known as ionic product of water.
It is designated as Kw
The value of Kw increases with the increase in temperature
Which of the following evolve hydrogen on reacting with cold dilute nitric acid?
Which of the following sulphides has the lowest solubility product ?
When ammonium chloride is added to ammonia solution, the pH of the resulting solution will be
Why only As⁺3 gets precipitated as As₂S₃ and not Zn⁺2 as ZnS when H₂S is passed through an acidic solution containing As⁺3 and Zn⁺2?
(CH₃)₂═CHCOCH₃ can be oxidised to (CH₃)₂C═CHCOOH by
Which is not true about acetophenone?
Conc. HNO3 forms NO2 + in presence of :
Which is not the resonance structure of aniline?
p-type silicon is formed by adding a minute amount of an element with
Following step is : CH3CH3 + Cl → CH3CH2 + HCl
In the following, electrophile is:
HO ― NO2
A solid AB has NaCl type structure. If radius of the cation A is 100 pm, then radius of the anion is
12 g of urea is dissolved in 1 litre of water and 68.4 g of sucrose is dissolved in 1 litre of water. The lowering of vapour pressure of first reaction is
Ultra-silicon is prepared by the process of
What weight of ferrous ammonium sulphate is needed to prepare 100 ml of 0.1 normal solution? (Eq wt. 392)
Equal volumes of 0.1 M AgNO₃ and 0.2 M NaCl are mixed. The concentration of NO₃- ions in the mixture will be
Which of the following properties are not correct for enantiomers?
Common oxidation state of scandium, a transition element, is/are [Ar.No.of Sc = 21]
The sulphate of an element contains 42.2% of the element. The equivalent weight the element would be (equivalent weight of sulphate = 48)
Apply the relation
Fossil remains of Archaeopteryx were recovered from the rock beds of the:
Which of the following are viral mosquito borne diseases?
G-6-P dehydrogenase deficiency is associated with the haemolysis of
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason(R) just below it. Read the Statement carefully and mark the correct answer-
Assertion(A): A total of 10 NADH2 and 2FADH2 molecules are formed in aerobic respiration.
Reason (R): NADH2 and 2FADH2 help in formation of 34 ATP molecules.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason(R) just below it. Read the Statement carefully and mark the correct answer-
Assertion(A): Carotene is a type of carotenoid.
Reason (R): Carotene is a precursor of vitamin A.
In the following question, a statement of Assertion(A) is given followed by a corresponding statement of Reason(R). Read the statements carefully, and mark the correct answer.
Assertion(A): In plant tissue culture, somatic embryos can be induced from any plant cell.
Reason(R): Any viable plant cell can differentiate into somatic embryos.
Any viable somatic cell of a plant has the ability to form full fledged plants. This ability of plant cell is known as cellular totipotency.
In the following question, a statement of Assertion(A) is given followed by a corresponding statement of Reason(R). Read the statements carefully, and mark the correct answer.
Assertion(A): When the ambient temperature is high and soil contains excess of water, the plants tend to lose water in the form of droplets from lenticels.
Reason(R): Root pressure regulates the rate of loss of water form lenticels.
When the ambient temperature is high and soil contains excess water, the rate of transpiration is increased i.e. loss of water takes place from leaves through stomata.
Lenticular transpiration is only 0.1% of the total transpiration. It however continues day and night because lenticels have no mechanism of closure. The lenticels connect the atmospheric air with the cortical tissue of stem through intercellular spaces present amongst the complementary cells. Root pressure regulates the rate of loss of water from the stomata in some plants.
In the following question, a statement of Assertion(A) is given followed by a corresponding statement of Reason(R). Read the statements carefully, and mark the correct answer.
Assertion(A): Photomodulation of flowering is a phytochrome - regulated process.
Reason(R): Active form of phytochrome (Pfr) directly induces floral induction in shoot buds.
Flowering is a phytochrome regulated process.Phytochrome is a blue protein pigment with a molecular mass of about 125 kDa.Phytochrome occurs in two interconvertible forms PR which absorbs red light and PFR which absorbs far red light.
PFR is active form of phytochrome.When PR molecules are exposed to red light most of them absorb it and are then converted to PFR. This cnversion causes floral induction in the shoot.
In the following questions, a statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the statements carefully and mark the answer-
Assertion (A): Lysosomes are formed by Golgi complex.
Reason (R): Golgi complex forms plasmalemma and cell wall.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason(R) just below it. Read the Statement carefully and mark the correct answer-
Assertion(A): Guard cells are specialised epidermal cells.
Reason (R): Stomata are found in the epidermis of leaves.
In the following question, a statement of Assertion(A) is given followed by a corresponding statement of Reason(R). Read the statements carefully, and mark the correct answer.
Assertion(A): Cancer is contagious and cells can spread from one person to other.
Reason(R): Cancerous cells are highly dedifferentiated cells.
Cancer is not contagious but the cancerous cells are higly differentiated cells. Cancer is the result of a continuous , abnormal and relatively autonomous cell proliferation which is due to the permanent alteration of some cells that gets transmitted to cell family. Cancer is a disease caused by losing the control over a cell's capacity to reproduce. The cancerous cell continues to divide and multiply abnormally until a detectable lump of tumour develops.
In the following question, a statement of Assertion(A) is given followed by a corresponding statement of Reason(R). Read the statements carefully, and mark the correct answer.
Assertion(A): In cells engaged in active secretion, as in pancreas, the rough endoplasmic reticulum is well developed.
Reason(R): Ribosomes attached to endoplasmic reticulum are actively engaged in protein synthesis.
Rough endoplasmic reticulum possess rough membrane due to presence of a number of ribosomes attached to their outer surfaces.Therefore RER is also called granular endoplasmic reticulum. The membrane of the endoplasmic reticulum bears a fine pore in the area of attached ribosome which passes the synthesised polypeptide into the channel of endoplasmic reticulum for transport. RER contains two types of glycoproteins (ribophorin I and ribophorin II) for attachment to ribosomes. The rough ER is engaged in synthesising proteins and enzymes, due to the presence of of ribosomes. It is, rich in cells which are actively engaged in protein synthesis and secretory activity, e.g., pancreatic acinus cells, plasma cells, fibroblasts, goblet cells.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason(R) just below it. Read the Statement carefully and mark the correct answer-
Assertion(A): Iron and copper mostly act as electron carriers.
Reason (R): Iron and copper possess variable valency.
In the following question, a statement of Assertion(A) is given followed by a corresponding statement of Reason(R). Read the statements carefully, and mark the correct answer.
Assertion(A): Severe Acute Respiratory Syndrome (SARS) originated in China.
Reason(R): China is the most poulated country of the world.
Severe Acute Respiratory Syndrome (SARS) a severe acute type of pneumonia caused by metapneumo virus was first reported in China.
Though China is the most populated country of the world it is not directly responsible for the origin of SARS. The killer pneumonia virus is responsible for SARS origin.
In the following question, a statement of Assertion(A) is given followed by a corresponding statement of Reason(R). Read the statements carefully, and mark the correct answer.
Assertion(A): Organochlorine pesticides are organic compounds that have been chlorinated.
Reason(R): Fenitrothion is one of the organochlorine pesticides.
Oragnochlorine pesticides are organic compounds or hydrocarbons to which several atoms of chlorine are added through the process called chlorination. Rate of degradation of organochlorines is very low.
Fenitrothion is organophosphate pesticide which is the organic ester of phosphoric acid and its derivates.These pesticides are very toxic but are not persistant.
In the following question, a statement of Assertion(A) is given followed by a corresponding statement of Reason(R). Read the statements carefully, and mark the correct answer.
Assertion(A): Chlorofluorocarbons are responsible for ozone depletion.
Reason(R): Ozone level decrease by as much as 67% every year.
A slight thinning of ozone layer occurs naturally for a few months every year over Antarctica. It decreases by 67% every year.The primary chemicals responsible for ozone depletion are a group of chlorine containing compounds called Chloroflurocarbons (CFCs), used as coolants in air aonditioners and refrigerators and propellants for aerosol cans and form blowing agents for insulation and packaging and also as solvents. Besides halons, methyl bromide, methyl chloroform, carbon tetrachloride and nitorus oxide are also responsible for O3 loss. After their release into troposphere, CFCs and other chlorine containing compounds go to stratosphere where these are broken down by UV- radiations releasing chlorine. Similarly bromine is released by breakdown of halons and methly bromide. The sunlight catalyses the chemical reactions by which chlorine or bromine break O3 molecules and convert them into O2 molecules. This chemical reaction does not change chlorine or bromine and thus single chlorine or bromine atom can breakdown many thousands of O3 molecules.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason(R) just below it. Read the Statement carefully and mark the correct answer-
Assertion(A): Retenone is an extremely toxic insecticide.
Resaon (R): Retenone interrupts electron transport chain in the cells of insect body.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason(R) just below it. Read the Statement carefully and mark the correct answer-
Assertion(A): Stipules are functionally insignificant organs of plant.
Reason (R): Stipel is a small stipule.
In the following question, a Statement of Assertion (A) is given followed by a corresponding Reason(R) just below it. Read the Statement carefully and mark the correct answer-
Assertion(A): Sweet potato has reproductive roots.
Reason (R): Adventitious buds are roots.
In the following question, a statement of Assertion(A) is given followed by a corresponding statement of Reason(R). Read the statements carefully, and mark the correct answer.
Assertion(A): The age-sex structure of human population in countries like France and Germany gives a steep pyramid.
Reason(R): In countries like Sudan and India the population is increaseing at a rapid rate.
The most important demographic characteristic of a population is its age sex structure which is also known as population pyramids. Age sex pyramids display the percentage or actual amount of a population broken down by gender and age. Developed countries with stable population gives a steep pyramid.
The population of Sudan and India are increasing at a rapid rate. The population growth rate for Sudan is 2.60% and for India it is 1.40%.
In the following questions, a statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the statements carefully and mark the answer-
Assertion (A): If isolated cells of a sponge are kept together, they adhere and form an intact sponge.
Reason (R): Plasma membranes of the adjacent cells form various types of junctions for keeping the cells together.
In the following questions, a statement of Assertion (A) is given followed by a corresponding Reason (R) just below it. Read the statements carefully and mark the answer-
Assertion (A): Mitochondria is an important cell organelle of both eukaryotes and prokaryotes.
Reason (R): They are called power house.
Lactose is a polysaccharide of
Succus entericus is the name given to
Which of the following is a characteristic of systemic circulation?
Which of the following enzymes helps in alcoholic fermentation?
In the following question, a statement of Assertion(A) is given followed by a corresponding statement of Reason(R). Read the statements carefully, and mark the correct answer.
Assertion(A): Secreting hypotonic urine is effective in reducing urinary loss of water.
Reason(R): Hypotonic urine is more concentrated and higher in osmotic pressure than the blood.
When there is a threat of excessive water loss from the body of the animal then the urine excreted needs to be hypertonic and not hypotonic because excessive water loss from the body possess the threat of a rise in osmoconcentration of blood. Since hypertonic urine is more concentrated and higher in osmotic pressure than the blood, therefore it helps in reducing the loss of water with urine.
Human urine is hypertonic which is more concentrated than the blood.So an isotonic glomeruler filterate is first filtered into the Bowman's capsules of nephrons in kidneys. The tubules of nephrons then reabsorb a large volume of water from the glomerular filtrate not accompained by the reabsorption of proportionate amounts of solutes. This leaves the urine more concentrated than the blood which is very effective in reducing the urinary loss of water.
DNA strands are antiparallel because of the presence of :
Enzyme needed for production of DNA from RNA is
Kadiri-1 and Kadiri-2 are the varieties of
The latest trend in plant disease control is
The Indian soils are generally poor in
The evolution of genera 'Homo' occured in
DNA replication in eucaryotes commences
When dominant and recessive alleles express themselves together, they are called
Cells involved in immune mechanism are
Turner's syndrome does not occur in males(44 + Y) because
Suspension of attenuated pathogen that stimulates antibody formation is
Interferons are synthesised in response to
Which one does not contribute to nitrogen availability in the soil?
Cornea transplantation has become common due to
Gram (-) ve bacteria possess peptidoglycan and an extra layer of
Neurotransmitters may create an action potential when they
Hypanthodium is
Heterocysts that take part in nitrogen fixation occur in
Photosynthesis is the fastest in
Transduction in bacteria is mediated by
Vessels differ from tracheids
Carbon dioxide is formed in all the following except
Enucleate thin-walled cells with perforated septa are
Atmosphere of big/metropolitan cities is polluted most by