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Medical
218 Views   |

Which of the following statements is not correct for a nucleophile?

• Option 1)

Nucleophile is a Lewis acid

• Option 2)

Ammonia is a nucleophile

• Option 3)

Nucleophiles attack on less e- density sites

• Option 4)

Nucleophiles are not electron seeking

As we learnt in Nucleophile - Those e- rich  chemical species having capacity to attack e-deficient portion of substrate. - wherein Nucleophile must have complete octet and atleast one lone pair    Nucleophiles are those compounds which has a lone pair of electron . Lewis acid has deficiency of electron. Hence a nucleophile can't be a Lewis acid.    Option 1) Nucleophile is a Lewis...
Medical
469 Views   |

The number of structural isomers possible from the molecular formula C3H9N is:

• Option 1)

4

• Option 2)

5

• Option 3)

2

• Option 4)

3

As we learnt in Isomerism in nitro compounds - Nitroalkanes shows chain, position, functional isomerism and Tautomerism. -       Option 1) 4 Correct Option 2) 5 Incorrect Option 3) 2 Incorrect Option 4) 3 Incorrect
Medical
350 Views   |

An electron moves on a straight line path XY as shown. The abcd is a coil adjacent to the path of electron What will be the direction of current if any, induced in the coil?

• Option 1)

• Option 2)

The current will reverse its direction as the electron goes past the coil

• Option 3)

No current induced

• Option 4)

abcd

Faraday’s First Law - Whenever the number of magnetic lines of force (Magnetic Flux) passing through a circuit changes an emf called induced emf is produced in the circuit.    -    Initially electron is approaching the coil and then its leaving the coil. Hence first flux will increase and then decrease. Direction as electron goes past the coil. Option 1) adcb This is incorrect option Option...
Medical
368 Views   |

Reaction of phenol with chloroform in presence of dilute sodium hydroxide finally introduces which one of the following functional group?

• Option 1)

-CH2Cl

• Option 2)

-COOH

• Option 3)

-CHCl2

• Option 4)

-CHO

Reimer Tiemann's reaction - The electrophile used is CCl2  (Dichloromethylene) -CHO is introduced in the ortho position. - wherein     Option 1) -CH2Cl This option is incorrect  Option 2) -COOH This option is incorrect  Option 3) -CHCl2 This option is incorrect  Option 4) -CHO This option is correct
Medical
118 Views   |

Which of the following reaction(s) can be used for the preparation of alkyl halides?

(I)       $CH_{3}CH_{2}OH+HCl\overset{anh.ZnCl_{2}}{\rightarrow}$

(II)       $CH_{3}CH_{2}OH+HCl \rightarrow$

(III)       $(CH_{3})_{3}COH+HCl \rightarrow$

(IV)       $(CH_{3})_{2}CHOH+HCl \overset{anh.ZnCl_{2}}{\rightarrow}$

• Option 1)

(I), (III) and (IV) only

• Option 2)

(I) and (II) only

• Option 3)

(IV) only

• Option 4)

(III) and (IV) only

As we learnt in  Alcohols reaction with hydrogen halides - Forms alkyl halides. - wherein    Tertiary alcohols forms alkyl halides but not easily due to the higher stability of tertiary carbocation  Option 1) (I), (III) and (IV) only This solution is correct  Option 2) (I) and (II) only This solution is incorrect  Option 3) (IV) only This solution is incorrect  Option 4) (III) and (IV)...
Medical
108 Views   |

Which of the following statements is not correct for a nucleophile ?

• Option 1)

Nucleophile is a Lewis acid

• Option 2)

Ammonia is a nucleophile

• Option 3)

Nucleophiles attack low e- density sites

• Option 4)

Nucleophiles are not electron seeking

As we learnt in Nucleophile - Those e- rich  chemical species having capacity to attack e-deficient portion of substrate. - wherein Nucleophile must have complete octet and atleast one lone pair    Nucleophiles are those having capacity to donate electrons s.e they, Lewis base     Option 1) Nucleophile is a Lewis acid This option is correct. Option 2) Ammonia is a nucleophile This option is...
Medical
132 Views   |

Method by which Aniline cannot be prepared is :

• Option 1)

hydrolysis of phenylisocyanide with acidic solution.

• Option 2)

degradation of benzamide with bromine in alkaline solution.on.

• Option 3)

reduction of nitrobenzene with H2/Pd in ethanol.

• Option 4)

potassium salt of phthalimide treated with chlorobenzene followed by hydrolysis with aqueous NaOH solution.

As we learnt in Gabriel Phthalimide Synthesis - Further alkylation can be stopped and a pure primary amine can be obtained by alkylation of phthalimide ( Gabriel synthesis ) followed by hydrolysis. - wherein    Gabrief Alkalimide synthesis of primary amines.  Because there exist partial double between chlorine and carbon.   Option 1) hydrolysis of phenylisocyanide with acidic...
Medical
248 Views   |

A gas such as carbon monoxide would be most likely to obey the ideal gas law at:

• Option 1)

high temperatures and low pressures.

• Option 2)

low temperatures and high pressures.

• Option 3)

high temperatures and high pressures.

• Option 4)

low temperatures and low pressures.

As we learned in concept no Kinetic Theory of Gases - Molecules of gases are very small and their actual volume is negligible in comparision to the empty space between them. -    Ideal gas behaviour is based on the following assumption molecules of gases are very small and their actual volume is negligible in comparision to the empty space between them There is no force of attraction between...
Medical
84 Views   |

Point masses m1 and m2 are placed at the opposite ends of a rigid rod of length L, and negligible mass. The rod is to be set rotating about an axis perpendicular to it. The position of point P on this rod through which the axis should pass so that the work required to set the rod rotating with angular velocity is minimum, is given by :

• Option 1)

• Option 2)

• Option 3)

• Option 4)

As we learned in concept Moment of inertia for system of particle -   - wherein Applied when masses are placed discretely.    Total M.I of rod As I is minimum i.e. => Option 1) this is the incorrect option Option 2) this is the incorrect option Option 3) this is the correct option Option 4) this is the incorrect option
Medical
139 Views   |

An automobile moves on a road with a speed of 54 km h-1. The radius of its wheels is 0.45 m and the moment of inertia of the wheel about its axis of rotation is 3 kg m2. If the vehicle is brought to rest in 15 s, the magnitude of average torque transmitted by its brakes to the wheel is :

• Option 1)

8.58 kg m2 s-2

• Option 2)

10.86 kg m2 s-2

• Option 3)

2.86 kg m2 s-2

• Option 4)

6.66 kg m2 s-2

As we learned in concept Analogue of second law of motion for pure rotation - - wherein Torque equation can be applied only about two point (i) centre of motion. (ii) point which has zero velocity/acceleration.    V=54 Km/hr = 15m/s   Angular velocity of vehicle V=W0r Angular Accn          =>     Option 1) 8.58 kg m2 s-2 This option is incorrect. Option 2) 10.86 kg m2 s-2 This option is...
Medical
80 Views   |

A force is acting at a point . The value of &alpha; for which angular momentum about origin is conserved is:

• Option 1)

2

• Option 2)

zero

• Option 3)

1

• Option 4)

-1

Torque -       - wherein This can be calculated by using either  = perpendicular distance from origin to the line of force. = component of force perpendicular to line joining force.      L=              Option 1) 2 This option is incorrect. Option 2) zero This option is incorrect. Option 3) 1 This option is correct. Option 4) -1 This option is incorrect.
Medical
109 Views   |

Which one of the following hormones is not involved in sugar metabolism ?

• Option 1)

Aldosterone

• Option 2)

Insulin

• Option 3)

Glucagon

• Option 4)

Cortisone

Cortisol - In our body, cortisol is the main glucocorticoid. - wherein Corticoids, which regulate the balance of water and electrolytes in our body are called mineralocorticoids. Aldosterone is the main mineralocorticoid in our body.     Aldosterone - Aldosterone acts mainly at the renal tubules and stimulates the reabsorption of Na+ and water and excretion of K+ and phosphate ions. -...
Medical
94 Views   |

Which of the following joints would allow no movement ?

• Option 1)

Cartilaginous joint

• Option 2)

Synovial joint

• Option 3)

Ball and Socket joint

• Option 4)

Fibrous joint

Fibrous joints - Fibrous joints do not allow any movement. - wherein This type of joint is shown by the flat skull bones which fuse end-to-end with the help of dense fibrous connective tissues in the form of sutures, to form the cranium.     Option 1) Cartilaginous joint This option is incorrect. Option 2) Synovial joint This option is incorrect. Option 3) Ball and Socket joint This option...
Medical
111 Views   |

Which of the following is not a function of the skeletal system ?

• Option 1)

Storage of minerals

• Option 2)

Production of body heat

• Option 3)

Locomotion

• Option 4)

Production of erythrocytes

SKELETAL SYSTEM - Skeletal system consists of a framework of bones and a few cartilages. - wherein This system has a significant role in movement shown by the body.    Production of Heat is not by skeleton system. It provides support for movement, store minerals  and production of blood cells(Bonemarrow). Option 1) Storage of minerals This option is incorrect Option 2) Production of body...
Medical
117 Views   |

In mammalian eye, the 'fovea' is the center of the visual field, where:

• Option 1)

the optic nerve leaves the eye.

• Option 2)

only rods are present.

• Option 3)

more rods than cones are found.

• Option 4)

high density of cones occur, but has no rods.

Fovea - At the posterior pole of the eye lateral to the blind spot, there is a yellowish pigmented spot called macula lutea with a central pit called the fovea. - wherein The fovea is a thinned-out portion of the retina where only the cones are densely packed. It is the point where the visual acuity (resolution) is the greatest.    Only cones are densely packed and rodes Hu are...
Medical
108 Views   |

Which one of the following hormones though synthesised elsewhere, is stored and released by the master gland?

• Option 1)

Luteinizing hormone

• Option 2)

Prolactin

• Option 3)

Melanocyte stimulating hormone

• Option 4)

Antidiuretic hormone

Vasopressin - Vasopressin acts mainly at the kidney and stimulates resorption of water and electrolytes by the distal tubules and thereby reduces loss of water through urine (diuresis) - wherein Hence, it is also called as anti-diuretic hormone (ADH).     Osmoreceptors - Osmoreceptors in the body are activated by changes in blood volume, body fluid volume and ionic concentration. - wherein An...
Medical
124 Views   |

The primary dentition in human differs from permanent dentition in not having one of the following type of teeth :

• Option 1)

Premolars

• Option 2)

Molars

• Option 3)

Incisors

• Option 4)

Canine

Decidous Teeth - In humans, first set of teeth are called the decodous teeth, which are 20 in number - wherein The dental formula is 2102/2102.  This means 2 incisors, 1 canine, 0 premolars, 2 molars    Premolars are absent 2102/2102 Option 1) Premolars This  is correct option Option 2) Molars This  is incorrect option Option 3) Incisors This  is incorrect option Option 4) Canine This  is...
Medical
266 Views   |

Human urine is usually acidic because :

• Option 1)

excreted plasma proteins are acidic.

• Option 2)

potassium and sodium exchange generates acidity.

• Option 3)

hydrogen ions are actively secreted into the filtrate.

• Option 4)

the sodium transporter exchanges one hydrogen ion for each sodium ion, in peritubular capillaries.

As we learnt Characteristics of urine - An adult human excretes, on an average, 1 to 1.5 litres of urine per day. - wherein The urine formed is a light yellow coloured watery fluid which is slightly acidic (pH-6.0) and has a characterestic odour.    The pH of urine is 6.0 which is acidic due to secretion of H+ ions H+ is proportional to 1/pH (low pH -> High H+) Option 1) excreted plasma...
Medical
170 Views   |

Doctors use stethoscope to hear the sounds produced during each cardiac cycle. The second sound is heard when :

• Option 1)

Ventricular walls vibrate due to gushing in of blood from atria

• Option 2)

Semilunar valves close down after the blood flows into vessels from ventricles

• Option 3)

AV node receives signal from SA node

• Option 4)

AV valves open up

As we learnt in  Lub-dub - During each cardiac cycle two prominent sounds are produced which can be easily heard through a stethoscope. - wherein The first heart sound (lub) is associated with the closure of the tricuspid and bicuspid valves whereas the second heart sound (dub) is associated with the closure of the semilunar valves.    The second heart sound (dub) is associated with the closure...
Medical
723 Views   |

A beam of light consisting of red, green and blue colours is incident on a right angled prism. The refractive index of the material of the prism for the above red, green and blue wavelengths are 1.39, 1.44 and 1.47, respectively.

The prism will:

• Option 1)

separate all the three colours from one another

• Option 2)

not separate the three colours at all

• Option 3)

separate the red colour part from the green and blue colours

• Option 4)

separate the blue colour part from the red and green colours

As we learnt in  Critical angle - = Refractive index of rarer medium / Refractive index of denser medium - wherein When angle of incidence of a travelling from a dence medium to rarer medium is greater than critical angle, no refraction occurs.  angle of incidence at surface AC= Critical Angle of incidence For red For green For blue Since refractive index of green and blue is greater...
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