100525 + Interview Questions in GENERAL QA IN GENERAL AWARENESS Page 131 InterviewSolution

6501.	The log - log graph between the energy `E` of an electron and its de - Broglie wavelength `lambda` will beA. B. C. D.
Answer» Correct Answer - C As we know that, wavelength of a particle `lambda=h/(sqrt(2mE))=h/(sqrt(2m)).1/(sqrt(E)) rArr log lambda=log(h/(sqrt(2m)).1/sqrt(E))` `rArr log lambda = logh/sqrt(2m) + log 1/E^(1//2)` `rArr loglambda=log(h/sqrt(2m))-1/2logE` `rArr loglambda=-1/2logE+logh/sqrt(2m)` So, equation of straight line is y=mx +c This is equation of line with slope `-1/2`

Discussion

6502.	The diode used at a constant potential drop of 0.5 V at all currents and maximum power rating of 100 mW. What resistance must be connected in series diode, so that current in circuit is maximum? A. `200 Omega`B. `6.67 Omega`C. `5 Omega`D. `15 Omega`
Answer» Correct Answer - C Current passing in the circuit is `I=P/V = (100 xx 10^(-3))/0.5 = 0.2 A` Value of connected series resistance, `R= (1.5 -0.5)/0.2 rArr R=1/0.2` `therefore R=5Omega`

Discussion

6503.	What is hemoglobin? What is the inorganic element that is fundamental in the composition of hemoglobin?
Answer» Hemoglobin is the protein present in the blood responsible for the transport of oxygen from the lungs to the tissues and cells. The hemoglobin molecule is composed of four protein chains, each with a heme group containing an iron atom. The iron is responsible for the binding of oxygen in the lungs and also for the red color of hemoglobin and thus of the blood.

6503.

What is hemoglobin? What is the inorganic element that is fundamental in the composition of hemoglobin?

Answer»

Hemoglobin is the protein present in the blood responsible for the transport of oxygen from the lungs to the tissues and cells.

The hemoglobin molecule is composed of four protein chains, each with a heme group containing an iron atom. The iron is responsible for the binding of oxygen in the lungs and also for the red color of hemoglobin and thus of the blood.

Discussion

6504.	What are the main biological processes in which calcium participates?
Answer» Calcium is present in almost all cells and has several functions. Calcium has an important role in muscular contraction, in the blood coagulation process, in the structure of bone tissue, in teeth, in the motility of the sperm cell flagellum and in the nervous transmission.

6504.

What are the main biological processes in which calcium participates?

Answer»

Calcium is present in almost all cells and has several functions.

Calcium has an important role in muscular contraction, in the blood coagulation process, in the structure of bone tissue, in teeth, in the motility of the sperm cell flagellum and in the nervous transmission.

Discussion

6505.	The half life of a radioactive substance is `20` minutes . The approximate time interval `(t_(2) - t_(1))` between the time `t_(2)` when `(2)/(3)` of it had decayed and time `t_(1)` when `(1)/(3)` of it had decay isA. 14 minB. 20 minC. 28 minD. 7 min
Answer» Correct Answer - B `therefore N_(1) = N_(0)-1/3N_(0)=2/3N_(0)` and `N_(2)=N_(0)-2/3N_(0)=1/3N_(0)` `therefore N_(2)/N_(1) = (1/2)^(n) rArr n=1` `therefore t_(2)-t_(1)` = one half-life = 20 min

Discussion

6506.	Is water a polar or a nonpolar molecule? What is the consequence of that characteristic for the function of water as solvent?
Answer» Water is made of two atoms of hydrogen attached by covalent bond with one central atom of oxygen making an angular spatial structure. The hydrogen atoms “lend” electrons to the oxygen and consequently this atom becomes more negative while the hydrogens become more positive. The spatial geometry of the water molecule makes it a polar molecule, with negative and positive poles. Water is an excellent solvent for polar substances because the electrical activity (attraction and repulsion) of its poles help the separation and the mixing of these substances, giving them more movement and thus increasing the number of molecular collisions and the speed of chemical reactions. On the another hand, water is not good as a solvent for non-polar substances Polarity is one of the water properties.

6506.

Is water a polar or a nonpolar molecule? What is the consequence of that characteristic for the function of water as solvent?

Answer»

Water is made of two atoms of hydrogen attached by covalent bond with one central atom of oxygen making an angular spatial structure. The hydrogen atoms “lend” electrons to the oxygen and consequently this atom becomes more negative while the hydrogens become more positive. The spatial geometry of the water molecule makes it a polar molecule, with negative and positive poles.

Water is an excellent solvent for polar substances because the electrical activity (attraction and repulsion) of its poles help the separation and the mixing of these substances, giving them more movement and thus increasing the number of molecular collisions and the speed of chemical reactions. On the another hand, water is not good as a solvent for non-polar substances

Polarity is one of the water properties.

Discussion

6507.	Energy of characteristic X-ray is a consequence of …………. (a) energy of projectile electron (b) thermal energy of target (c) transition in target atoms (d) none of the above
Answer» (c) transition in target atoms

Discussion

6508.	A radioactive element decays by `beta-emission`. A detector records `n` beta particles in `2 s` and in next `2 s` it records `0.75 n` beta particles. Find mean life correct to nearest whole number. Given ln `\|2\| = 0.6931`, ln `\|3\|=1.0986`.A. `17s`B. `7s`C. `5s`D. `15s`
Answer» Correct Answer - B Let `N_(0)=` initial number of nuclei `n = N_(0) - N_(0)e^(-lambda xx)` `1.75 n = N_(0) - N_(0)e^(-4lambda)` `(1)/(1.75) = (1-e^(-2lambda))/(1-e^(-4lambda))` `1+e^(-2lambda) = 1.75` `e^(2lambda) = (1)/(0.75) = 1.33` `2 lambda = ln (1.33)` `tau = (1)/(lambda) = (2)/(ln(1.33)) = 7s`

Discussion

6509.	The incorrect statement regarding `15 th` group hydrides `(EH_(3))[E=N,P,As,Sb,Bi]`A. `NH_(3)gtPH_(3)gtAsH_(3)gtSbH_(3)gtBiH_(3)` (Thermal Stability)B. `N-HgtP-HgtAs-H-Sb-HgtBi-H` (E-H bond Dissociation Enthalpy)C. `NH_(3)gtPH_(3)gtAsH_(3)gtSbH_(3)gtBiH_(3)` (Reducing Character)D. `NH_(3)gtPH_(3)gtAsH_(3)gtSbH_(3)gtBiH_(3)` (Basicity)
Answer» Correct Answer - C

Discussion

6510.	Correct order of `IP` is ?A. `S^(-)gtOgtSgtO^(-)`B. `OgtSgtO^(-)gtS^(-)`C. `OgtSgtS^(-)gtO^(-)`D. `S^(-)gtO^(-)gtOgtS`
Answer» Correct Answer - C

Discussion

6511.	`underset(("Lewis base"))(B_(2)H_(6)+2Lrarr2BH_(3)L)` `L` would be `:`A. `NH_(3)`B. `CH_(3)NH_(2)`C. `(CH_(3))_(2)NH`D. `(CH_(3))_(3)N`
Answer» Correct Answer - D

Discussion

6512.	The incorrect order of solubility in water `:-`A. `Ca(OH)_(2)gtSr(OH)_(2)gtBa(OH)_(2)`B. `Li_(2)CO_(3)ltNaCO_(3)ltK_(2)CO_(3)`C. `CaNO_(4)ltRbNO_(3)ltKNO_(3)`D. All of these
Answer» Correct Answer - A

Discussion

6513.	Which of the following require maximum amount of energy ?A. `NerarrNe^(+)+e^(ө)`B. `Be^(+2)rarrBe^(+3)+e^(ө)`C. `LirarrLi^(+)+e^(ө)`D. `MgrarrMg^(+)+e^(ө)`
Answer» Correct Answer - B

Discussion

6514.	Correct thermal stability order is `:-` `(a)` `BeSO_(4)ltMgSO_(4)ltCaSO_(4)ltSrSO_(4)ltBaSO_(4)` `(b)` `BeCO_(3)ltMgCO_(3)ltCaCO_(3)ltSrCO_(3)ltBaCO_(3)` `(c)` `HFgtH_(2)OgtNH_(3)gtCH_(4)` `(d)` `NH_(3)ltPH_(3)ltAsH_(3)ltSbH_(3)` correct option is `:-`A. a, b, cB. a, b, c, dC. only a, bD. None
Answer» Correct Answer - A

Discussion

6515.	Using the data given below, state which two of the given lenses will you prefer to construct a best possible :(i) telescope (ii) microscope Also, Indicate which of the selected lenses is to be used as an objective and as an eye piece in each case.LensesPower(P)Aperture(A)L16D1cmL23D8cmL310D1cm
Answer» For a telescope, Lens L₃ is chosen as objective, as its aperture is largest. The lens L₃ is chosen as eyepiece, As its focal length is smallest. For a microscope, Lens L₃ is chosen objective because its focal length is smallest. Lens L₁ serves as eye piece because its focal length is not largest. This is required to secure greater magnifying power of the microscope.

6515.

Using the data given below, state which two of the given lenses will you prefer to construct a best possible :(i) telescope (ii) microscope Also, Indicate which of the selected lenses is to be used as an objective and as an eye piece in each case.LensesPower(P)Aperture(A)L16D1cmL23D8cmL310D1cm

Answer»

For a telescope,

Lens L₃ is chosen as objective, as its aperture is largest.

The lens L₃ is chosen as eyepiece,

As its focal length is smallest.

For a microscope,

Lens L₃ is chosen objective because its focal length is smallest.

Lens L₁ serves as eye piece because its focal length is not largest.

This is required to secure greater magnifying power of the microscope.

Discussion

6516.	Correct thermal stability order is `:-` `(a)` `BeSO_(4)ltMgSO_(4)ltCaSO_(4)ltSrSO_(4)ltBaSO_(4)` `(b)` `BeCO_(3)ltMgCO_(3)ltCaCO_(3)ltSrCO_(3)ltBaCO_(3)` `(c)` `HFgtH_(2)OgtNH_(3)gtCH_(4)` `(d)` `NH_(3)ltPH_(3)ltAsH_(3)ltSbH_(3)` Correct option is `:`A. `a,b,c`B. `a,b,c,d`C. only `a,b`D. none
Answer» Correct Answer - A

Discussion

6517.	In a compound `AX_(4)` (no lone pair) `EN_(A)ltEN_(X)` then which of the following structures will result into zero dipole moment. (`A=`Centre of cube)A. `a` & `b`B. `a` & `c`C. `b` & `d`D. `c` & `d`
Answer» Correct Answer - D

Discussion

6518.	Resonance Hybrid of nitrate ion is `:`A. B. C. D.
Answer» Correct Answer - D

Discussion

6519.	A uniform string of length 10 m is suspended from a rigid support A short wave pulse is introduced at its lowest end it starts moving up the string the time taken to reach the support is (take `g=10m//sec^(2)`)A. 1 secB. 2 secC. `2sqrt(2)`D. 4 sec
Answer» Correct Answer - B Let mass per unit length be `mu`. Tension at a distance `x` from lowest point is `T=mugx` `V=sqrt((T)/(mu))=sqrt(gx)` `v^(2)=gx` `a=(vdv)/(dx)=(g)/(2)` `l=(1)/(2)((g)/(2))t^(2)` `t=sqrt((4l)/(g))=sqrt((4xx10)/(10))=2sec`.

Discussion

6520.	A uniform string of length 10 m is suspended from a rigid support A short wave pulse is introduced at its lowest end it starts moving up the string the time taken to reach the support is (take `g=10m//sec^(2)`)
Answer» Correct Answer - 2 Let mass per unit length be `mu`. Tension at a distance `x` from lowest point is `T=mugx` `v=sqrt((T)/(mu))=sqrt(gx),v^(2)=gx` `a=(vdv)/(dx)=(g)/(2),l=(1)/(2)((g)/(2))t^(2)` `t=sqrt((4l)/(g))=sqrt((4xx10)/(10))=2sec`

Discussion

6521.	Solve for `x :``2tan^(-1)(sinx)=tan^(-1)(2secx), x!=pi/2`
Answer» `2tan^-1(sinx) = tan^-1(2secx)` Applying `tan` both sides, `=> tan(2tan^-1(sinx)) = tan(tan^-1(2secx))` `=>(2tan(tan^-1(sinx)))/(1-tan^2(tan^-1(sinx))) = 2secx` `=>(2sinx)/(1-sin^2x) = 2secx` `=>sinx/cos^2x = 1/cosx` `=>six/cosx = 1` `=>tanx = 1` `=>x = npi+pi/4`

Discussion

6522.	Charges Q, 2Q and 4Q are uniformly distributed in three dielectric solid spheres 1, 2 and 3 of radii R/2, R and 2R respectively, as shown in figure. If magnitudes of the electric fields at point P at a distance R from the center of spheres 1, 2 and 3 are E1, E2 and E3 respectively, then(A) E1 > E2 > E3 (B) E3 > E1 > E2 (C) E2 > E1 > E3 (D) E3 > E2 > E1
Answer» (A) E₁ > E₂ > E₃ For point outside dielectric sphere E = Q/4π∈₀r² For point inside dielectric sphere E = E_s r/R Exact Ratio E₁ : E₂ : E₃ = 2 : 4 : 1

6522.

Charges Q, 2Q and 4Q are uniformly distributed in three dielectric solid spheres 1, 2 and 3 of radii R/2, R and 2R respectively, as shown in figure. If magnitudes of the electric fields at point P at a distance R from the center of spheres 1, 2 and 3 are E1, E2 and E3 respectively, then(A) E1 > E2 > E3 (B) E3 > E1 > E2 (C) E2 > E1 > E3 (D) E3 > E2 > E1

Answer»

(A) E₁ > E₂ > E₃

For point outside dielectric sphere E = Q/4π∈₀r²

For point inside dielectric sphere E = E_s r/R

Exact Ratio E₁ : E₂ : E₃ = 2 : 4 : 1

Discussion

6523.	A bob of mass m , suspended by a string of length l1 is given a minimum velocity required to complete a full circle in the vertical plane. At the highest point, it collides elastically with another bob of mass m suspended by a string of length l2, which is initially at rest. Both the strings are mass-less and inextensible. If the second bob, after collision acquires the minimum speed required to complete a full circle in the vertical plane, the ratio l1/l2 is
Answer» The initial speed of 1st bob (suspended by a string of length l₁)is \(\sqrt{5gl_1}\). The speed of this bob at highest point will be \(\sqrt{gl_1}.\) When this bob collides with the other bob there speeds will be interchanged. \(\sqrt{gl_1}=\sqrt{5gl_2}\) ⇒ \(\frac{l_1}{l_2}\) = 5

6523.

A bob of mass m , suspended by a string of length l1 is given a minimum velocity required to complete a full circle in the vertical plane. At the highest point, it collides elastically with another bob of mass m suspended by a string of length l2, which is initially at rest. Both the strings are mass-less and inextensible. If the second bob, after collision acquires the minimum speed required to complete a full circle in the vertical plane, the ratio l1/l2 is

Answer»

The initial speed of 1st bob (suspended by a string of length l₁)is \(\sqrt{5gl_1}\).

The speed of this bob at highest point will be \(\sqrt{gl_1}.\)

When this bob collides with the other bob there speeds will be interchanged.

\(\sqrt{gl_1}=\sqrt{5gl_2}\) ⇒ \(\frac{l_1}{l_2}\) = 5

Discussion

6524.	The speaker says that “Calendars and clocks are useless in space”. What might have been the reason for his opinion ?
Answer» The speaker says this statement because in space there is no work, no day and night or seasons. Totally there was no change in atmosphere, so there was no need of calender or clock.

Discussion

6525.	Assertion (A) : When cells are connected in parallel to the external load, the effective emf increases. Reason (R) : All the cells will be sending the current to the external load in the different directions.(a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true but R is NOT the correct explanation of A (c) A is true but R is false (d) A is false and R is also false
Answer» Option : (d) When the identical cells are connected in parallel, the effective emf is equal to emf of one cell. Hence, Assertion is wrong. Also, All the cells will be sending the current to the external load in the same direction. Hence, Reason is also wrong.

6525.

Assertion (A) : When cells are connected in parallel to the external load, the effective emf increases. Reason (R) : All the cells will be sending the current to the external load in the different directions.(a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true but R is NOT the correct explanation of A (c) A is true but R is false (d) A is false and R is also false

Answer»

Option : (d)

When the identical cells are connected in parallel, the effective emf is equal to emf of one cell.

Hence,

Assertion is wrong.

Also,

All the cells will be sending the current to the external load in the same direction.

Hence,

Reason is also wrong.

Discussion

6526.	Two bulbs 25W, 100 V (upper bulb in figure) and 100 W, 200 V (lower bulb in figure) are connected in the circuit as shown in figure. Choose the correct answer. A. Heat lost per second in the circuit will be 80 J.B. Ratio of heat produced per second in bulb will be `1:1`C. Ratio of heat produced in branch AB to that produced in branch CD will be `1:2`.D. Current drawn from the cell is 0.4A.
Answer» Correct Answer - A::D a.,d. Resistance of upper bulb, `R_1 = 100^2//25 = 400 Omega` Resistance of lower bulb, `R_2 = 200^2//100 = 400 Omega` Equivalent resistance of the circuit, `R_(eq) = 500 Omega` Heat lost per second in the circuit is `e^2//R_(eq) = 200^2//500 = 80Js^(-1)` Potential difference across branches AB and CD will be same. Hence, ratio of heat generated in them is `Heat_(AB)/Heat_(CD) = R_(CD)/R_(AB) = 1000/500 = 2:1` Hence, (c ) is incorrect. Since potential difference across branches AB and CD will be the same, but their resistances are different, so current in them will be different. As the resistances of the bulbs are same, so heat generated in them will be different. Hence, (b) is incorrect. Current drawn from the cell is `e//R_(eq) = 200//500 = 0.4A`.

Discussion

6527.	Assertion (A) : In series combination of electric bulbs, the bulb of lower power emits more light than that of higher power bulb.Reason (R) : The lower power bulb in series gets more current than the higher power bulb.(a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true but R is NOT the correct explanation of A (c) A is true but R is false (d) A is false and R is also false
Answer» Option : (c) In series, Resistance of bulb is higher for low power bulb than that of high power bulb.

6527.

Assertion (A) : In series combination of electric bulbs, the bulb of lower power emits more light than that of higher power bulb.Reason (R) : The lower power bulb in series gets more current than the higher power bulb.(a) Both A and R are true and R is the correct explanation of A (b) Both A and R are true but R is NOT the correct explanation of A (c) A is true but R is false (d) A is false and R is also false

Answer»

Option : (c)

In series,

Resistance of bulb is higher for low power bulb than that of high power bulb.

Discussion

6528.	I.` 8x^(2)+58x+39 = 0" "II.y^(2) - 35y+216=0`A. if`x lt y`B. if`x le y`C. if`x gt y`D. if`x ge y`
Answer» Correct Answer - A I. ` 8x^(2) + 58x+ 39 = 0` ` rArr 8x^(2) + 6x+52x+39 = 0` ` rArr (2x+13)(4x+3) = 0` `rArr x =- 3//4, -13//2` II. ` y^(2) - 35y+216 = 0` ` rArr y^(2) - 27y - 8y + 216 = 0` `rArr (y - 27)(y-8) = 0` ` rArr y = 27, 8` ` y gt x`

Discussion

6529.	In Bohr model of hydrogen atom, let `R,v` and `E` represent the radius of robit, speed of the electron and total energyy of electron respectively. Which of following quantities are directly proportional to quantum number `n`?A. `vR`B. `RE`C. `v/E`D. `R/E`
Answer» Correct Answer - A::C `vprop Z/n, Rprop(n^(2))/Z` and `Eprop (Z^(2))/(n^(2))` `impliesvRpropn` and `v/Epropn`

Discussion

6530.	`1 kg` ice at `-10^(@)C` is mixed with `0.1 kg` of steam at `200^(@)C`. If final temperature of mixture at equilibrium is `T_(eq)=(58x)/11`, then fill the vallue of `x` Latent heat of fusion of ice `=80` cal/gram, latent heat of vaporization of water `=540` cal/gram, specific heat capacity of ice `~=` specific heat of water `=0.5` cal/gram-K`
Answer» Correct Answer - 5 `1xx 1/2 xx 10+1xx80+1xx1xxT_("eq")=0.1xx1/2xx100+0.1xx540+0.1xx(100-T_("eq"))` `T_("eq")=290/11 K=58/11xx5`

Discussion

6531.	A neutron having kinetic energy `E_(0)` collides with singly ionised He atom at rest and move along initial direction. Which of the following statement(s) is/are true for the above mentioned collision.A. Collision will be perfectly inelastic if `E_(0)=17eV`B. Collision will be perfectly inelastic is `E_(0)=8.16eV`C. If `E_(0)=` then ploton of wavelength `lamda=500m` is observed just after the collision if `E_(0)=8.16eV`.D. Perfectly elastic collision is not possible.
Answer» Correct Answer - A::B::D `mv_(0)=(4m+m)v` `v=(v_(0))/5` `1/2mv_(0)^(2)=1/2.(5m).(v_(0)^(2))/25+/_E` `1/2 mv_(0)^(2)-1/2 . (v^(2))/25m=/_E` `implies 1/2 mv_(0)^(2) {4/5}=/_E` `1/2 mv_(0)^(2)=5/4/_E` `/_E=13.6` `/_E=13.6{1- 1/6}=3/4/ (13.6)` `1/2 mv_(0)^(2)=5/4xx13.6 3/5xx13.6` `=17 eV, 8.16 eV`

Discussion

6532.	Statement I: Electromagnetic waves are transverse in nature.Statement II: Electromagnetic waves can be polarised.Of these statements:(a) Both the statements are true and Statement It is the correct explanation of Statement I.(b) Both the statements are true, but Statement II is not the correct explanation of Statement I.(c) Statement I is true, but Statement II is false(d) Statement I is false, but Statement II is true.
Answer» (b) Both the statements are true, but Statement II is not the correct explanation of Statement I.

Discussion

6533.	Statement I: All nucleii are not of same size.Statement II: The size of nucleus depends on atomic mass.Of these statements:(a) Both the statements are true and Statement It is the correct explanation of Statement I.(b) Both the statements are true, but Statement II is not the correct explanation of Statement I.(c) Statement I is true, but Statement II is false(d) Statement I is false, but Statement II is true.
Answer» (a) Both the statements are true and Statement It is the correct explanation of Statement I.

Discussion

6534.	Statement-1: The mutual inductance of two concentric conducting rings of different radii is maximum if the rings are also coplanar. Statement-2: For two coaxial conducting rings of different radii, the magnitude of magnetic flux in one ring due to current in other ring is maximum when both rings are coplanar.A. Statement-1 is true, statement-2 is true and statement-2 is correct explanation for statement-1.B. Statement-1 is true, statement-2 is true and statement-2 is NOT the correct explanation for statement-1.C. Statement-1 is true, statement-2 is false.D. Statement -1 is false, statement -2 is true.
Answer» Correct Answer - B Because flux is maximum when rings are coplaner

Discussion

6535.	In the arrangements as shown Mgt2m. Find the extension in the spring of forces constant `K_(1)`. All pulleys are smooth and massless and the blocks do not oscillates. A. `(Mmg)/(K_(1)(M+m))`B. `(4Mmg).((M+m)).K/(K_(1))`C. `(Mmg)/(K_(1)(M+2m))`D. `(4Mmg)/(K_(1)(M+2m))`
Answer» Correct Answer - 4 `a=((M-2m)g)/((M+2m))` Now, `Mg-K_(1)x_(1)=Ma` `x_(1)=(M(g-a))/(K_(1))` `=(4Mmg)/(K_(1)(M+2m))`

Discussion

6536.	There are two concentric and coplanar non-conducting rings of radii `R` and `4R`. The charge is distributed uniormly on both rings. The charge on smaller ring is `q` and charge on large ring is `-8q`. A particle of mass `10g` and charge `-q` is projected along the axis from infinity. What is the minimum speed of charge at infinity to reach the common centre of rings (take `(Kq^(2))/R=(2sqrt(5))/3J`)A. `5m//s`B. `10m//s`C. `20m//s`D. `30m//s`
Answer» Correct Answer - C `vecE_(q)+vecE_(8q)=vec0` `implies(Kqx)/((R^(2)+x^(2))^(3//2))=(k(8q)x)/((16R^(2)+x^(2))(3//2))` `impliesx=2R` In region `xgt2R` electrostatics force is repulsive in region `0ltxlt2R` electrostatics force is attractive If change paticle crosses `x=2R` it will reach origin so by conservation of energy `:. 1/2mv^(2)=-(kqxxq)/(sqrt(R^(2)+x^(2)))+(k(8q)xxq)/(sqrt(16R^(2)+x^(2)))` `implies v=20m//s`

Discussion

6537.	In the arrangements as shown, blocks A and B of the masses as shown move in the direction with velocities as indicated on a smooth surface. The spring constant is 300 N/m. find the maximum compression in the spring (approx). A. 17 cmB. 22 cmC. 32 cmD. 38 cm
Answer» Correct Answer - 3 `1/2 mu v_(r)^(2)=1/2 kx_(m)^(2)` `1/2xx5/6xx6^(2)=1/2 xx300 x_(m)^(2)`

Discussion

6538.	The floods in the State of Tamil Nadu, adversely affected the area causing destruction to life, property, cattle and crops. As a news correspondent, you visited this state. Write the details of this disaster in 150-200 words. Also give a suitable title to your write up.
Answer» Devastation By Floods [XYZ, News Correspondent, The Express] A visit to the flood-hit districts of the State of Tamil Nadu fills one with depressing thoughts. How can nature be so cruel? The cyclonic storm has proved a disaster for the state. Coastal areas have been hit hard. The villages and hamlets have been adversely affected. Thousands of acres of land having crops are still submerged in water. Millions of cattle have been washed away or perished in the flood waters. Thousands of the villagers have been rendered homeless. Hundreds of children and the aged have been swept off. Thus there has been an all round destruction of life, property, cattle and crops. Government agencies and voluntary groups have rushed to the help of the flood-affected victims. The situation is grim and calls for more concerted efforts.

6538.

The floods in the State of Tamil Nadu, adversely affected the area causing destruction to life, property, cattle and crops. As a news correspondent, you visited this state. Write the details of this disaster in 150-200 words. Also give a suitable title to your write up.

Answer»

Devastation By Floods

[XYZ, News Correspondent, The Express]

A visit to the flood-hit districts of the State of Tamil Nadu fills one with depressing thoughts. How can nature be so cruel? The cyclonic storm has proved a disaster for the state. Coastal areas have been hit hard. The villages and hamlets have been adversely affected. Thousands of acres of land having crops are still submerged in water. Millions of cattle have been washed away or perished in the flood waters.

Thousands of the villagers have been rendered homeless. Hundreds of children and the aged have been swept off. Thus there has been an all round destruction of life, property, cattle and crops. Government agencies and voluntary groups have rushed to the help of the flood-affected victims. The situation is grim and calls for more concerted efforts.

Discussion

6539.	The three graphs shwon here show the total energy output of four different stars per second plotted against the wavelength that they radiate. All the four stars are behaving like black bodies. They can be assumed to be spherical bodies. Study the graphs below and answer the following questions. Take `b=3xx10^(-3) mK`. Which of the following is the correct order of the radius of star A , Star C and Star D?A. `R_(A) gt R_(C) gt R_(D)`B. `R_(A)=R_(D) gt R_(C)`C. `R_(D) gt R_(A) gt R_(C)`D. `R_(A) gt R_(D) gt R_(C)`
Answer» Correct Answer - C

Discussion

6540.	The three graphs shwon here show the total energy output of four different stars per second plotted against the wavelength that they radiate. All the four stars are behaving like black bodies. They can be assumed to be spherical bodies. Study the graphs below and answer the following questions. Take `b=3xx10^(-3) mK`. Which of the following statements correctly describes star C?A. It appears to be red in color and has temperature of 8000 KB. It appears to be blue in color and has temperature less than 8000 KC. It appears to be blue in color and has temperature 8000 KD. It appears to be red in color and has temperature more than 800 K
Answer» Correct Answer - C

Discussion

6541.	A particle of mass `2kg` moves under a force given by `vec(F)=-(8N//m)(xhat(i)+yhat(j))` where `hat(i)` and `hat(j)` are unit vectors in the `x` and `y` directions. The particle is projected from a point on `x` axis at `x=a` in `xy` plane with an initial velocity `vec(v)=v_(0)hat(j)`. Select correct statement (s). The particle will move inA. An elliptical path if `(v_(0))/a=3s^(-1)`B. A circular path if `(v_(0))/a=5s^(-1)`C. A circular path if `(v_(0))/a=2s^(-1)`D. An elliptical path if `(v_(0))/a=1s^(-1)`
Answer» Correct Answer - A::C::D For circular path amplitude of SHM along both axis must be same. `v_(0)=aomega`

Discussion

6542.	A particle of mass `2kg` moves under a force given by `vec(F)=-(8N//m)(xhat(i)+yhat(j))` where `hat(i)` and `hat(j)` are unit vectors in the `x` and `y` directions. The particle is projected from the origin in `xy` plane with an initial velocity `vec(v)=(3m//s)hat(i)+(4m//s)hat(j)`. Select correct statement(s).A. Time after which the particle will return to origin first timeis `pi//2` secB. Time after which the particle will return to origin first time is `pi` secC. The maximum disance between the particle and origin is `2m`D. The maximum distance between the particle and origin is `2.5m`
Answer» Correct Answer - A::D The `x` and `y` both coordinates oscillates simple harmonically is same plane. `omega =sqrt(k/m)=1rad//s` `T=pis` `A_(x)=(u_(x))/(omega)=1.5m` `A_(y)=(u_(y))/(omega)=2m` Net amplitude `=sqrt(A_(x)^(2)+A_(y)^(2))=2.5m`

Discussion

6543.	A particle of mass `2kg` moves under a force given by `vec(F)=-(8N//m)(xhat(i)+yhat(j))` where `hat(i)` and `hat(j)` are unit vectors in the `x` and `y` directions. The particle is projected from the origin in `xy` plane with an initial velocity `vec(v)=(3m//s)hat(i)+(4m//s)hat(j)`. Select correct statement(s).A. An elliptical path if `(v_(0))/a=3s^(-1)`B. A circular path if `(v_(0))/a=5s^(-1)`C. A circular path if `(v_(0))/a=2s^(-1)`D. An elliptical path if `(v_(0))/a=1s^(-1)`
Answer» Correct Answer - A::C::D For circular path amplitude of SHM along both axis must be same. `v_(0)=aomega`

Discussion

6544.	Find the ratio of charges on `5muF` and `10muF` capacitor when circuit is in steady state. All the batteries are ideal. A. `3/4`B. `1/4`C. `1/2`D. `2`
Answer» Correct Answer - A Voltage across `5muF=30V` Charge of `5muF=150muC` Voltage across `10muF=20mV` Charge on `10muF=200muC`

Discussion

6545.	Find the ratio of charges on `5muF` and `10muF` capacitor when circuit is in steady state. All the batteries are ideal. A. `3/4`B. `1/4`C. `1/2`D. `2`
Answer» Correct Answer - A Voltage across `5muF=30V` Charge of `5muF=150muC` Voltage across `10muF=20mV` Charge on `10muF=200muC`

Discussion

6546.	A ball is made of a material of density ρ where ρoil < ρ < ρwater with roil and ρwater representing the densities of oil and water, respectively. The oil and water are immiscible. If the above ball is in equilibrium in a mixture of this oil and water, which of the following pictures represents its equilibrium position ?
Answer» 2 ρ_oil < ρ < ρ_water Oil is the least dense of them so it should settle at the top with water at the base. Now the ball is denser than oil but less denser than water. So, it will sink through oil but will not sink in water. So it will stay at the oil–water interface.

6546.

A ball is made of a material of density ρ where ρoil < ρ < ρwater with roil and ρwater representing the densities of oil and water, respectively. The oil and water are immiscible. If the above ball is in equilibrium in a mixture of this oil and water, which of the following pictures represents its equilibrium position ?

Answer»

2

ρ_oil < ρ < ρ_water

Oil is the least dense of them so it should settle at the top with water at the base. Now the ball is denser than oil but less denser than water. So, it will sink through oil but will not sink in water. So it will stay at the oil–water interface.

Discussion

6547.	The trajectory of a projectile is given by `y=x tantheta-(1)/(2)(gx^(2))/(u^(2)cos^(2)theta)`. This equation can be used for calculating various phenomena such as finding the minimum velocity required to make a stone reach a certain point maximum range for a given projection velocity and the angle of projection required for maximum range. The range of a particle thrown from a tower is define as the distance the root of the tower and the point of landing. In the previous problem, what should be the corresponding projection angle.A. `tan^(-1) (1//2)`B. `tn^(-1)(1//3)`C. `tan^(-1)2`D. `tan^(-1)3`
Answer» Correct Answer - C `H = R tan theta - (1)/(2) g. (R^(2))/(u^(2)) (1 + tan^(2) theta)` `dy // d theta = 0` `tan theta = (u^(2))/(Rg) = (100)/(5 xx 10) = 2 rArr theta = tan^(-1) 2`

Discussion

6548.	For sound waves, the Doppler formula for frequency shift differs slightly between the two situations: (i) source at rest; observer moving, and (ii) source moving; observer at rest. The exact Doppler formulas for the case of light waves in vacuum are, however, strictly identical for these situations. Explain why this should be so. Would you expect the formulas to be strictly identical for the two situations in case of light travelling in a medium?
Answer» No Sound waves can propagate only through a medium. The two given situations are not scientifically identical because the motion of an observer relative to a medium is different in the two situations. Hence, the Doppler formulas for the two situations cannot be the same. In case of light waves, sound can travel in a vacuum. In a vacuum, the above two cases are identical because the speed of light is independent of the motion of the observer and the motion of the source. When light travels in a medium, the above two cases are not identical because the speed of light depends on the wavelength of the medium.

6548.

For sound waves, the Doppler formula for frequency shift differs slightly between the two situations: (i) source at rest; observer moving, and (ii) source moving; observer at rest. The exact Doppler formulas for the case of light waves in vacuum are, however, strictly identical for these situations. Explain why this should be so. Would you expect the formulas to be strictly identical for the two situations in case of light travelling in a medium?

Answer»

No
Sound waves can propagate only through a medium. The two given situations are not scientifically identical because the motion of an observer relative to a medium is different in the two situations. Hence, the Doppler formulas for the two situations cannot be the same.

In case of light waves, sound can travel in a vacuum. In a vacuum, the above two cases are identical because the speed of light is independent of the motion of the observer and the motion of the source. When light travels in a medium, the above two cases are not identical because the speed of light depends on the wavelength of the medium.

Discussion

6549.	Feeling the tremors of an earthquake a scared resident of seventh floor of a multistoryed building starts climbing down the stairs rapidly which hormone initiated this action? (A) Thyroxin (B) Adrenalin (C) Glucagon (D) Gastrin
Answer» Correct option (B) Adrenalin Explanation: Adrenalin hormone secreted by Adrenal Medulla prepares an individual during emergency or stress situations.

6549.

Feeling the tremors of an earthquake a scared resident of seventh floor of a multistoryed building starts climbing down the stairs rapidly which hormone initiated this action? (A) Thyroxin (B) Adrenalin (C) Glucagon (D) Gastrin

Answer»

Correct option (B) Adrenalin

Explanation:

Adrenalin hormone secreted by Adrenal Medulla prepares an individual during emergency or stress situations.

Discussion

6550.	A man is admitted in a hospital. He is suffering from an abnormally low body temperature, loss of appetite and extreme thirst. His brain scan would probably show a tumour in : (A) Medulla oblongata (B) Pons Varolli (C) Cerebellum (D) Hypothalamus
Answer» Correct option (D) Hypothalamus Explanation: Hypothalamus is centre for hunger, thirst, sweating, sleep, fatigue, temperature, anger, pleasure, love hate, and satisfaction. Thus, if a man is suffering from given abnormalities, he has a tumour in his hypothalamus.

6550.

A man is admitted in a hospital. He is suffering from an abnormally low body temperature, loss of appetite and extreme thirst. His brain scan would probably show a tumour in : (A) Medulla oblongata (B) Pons Varolli (C) Cerebellum (D) Hypothalamus

Answer»

Correct option (D) Hypothalamus

Explanation:

Hypothalamus is centre for hunger, thirst, sweating, sleep, fatigue, temperature, anger, pleasure, love hate, and satisfaction. Thus, if a man is suffering from given abnormalities, he has a tumour in his hypothalamus.

Discussion

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