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Which of the following amines can be synthesized by Gabriel phthalimide reaction (1) Neopentylamine (2) n-butylamine (3) Triethylamine (4) t-butylamine

Answer: (2) n-butylamine The phthalimide forms primary amines through nucleophilic substitution with an alkyl halide. Only one carbon and two... View Article

An aeroplane has to go from a point A to Point B, 500km away due 30o East of north. A wind is blowing due north at a speed of 20m/s. The air speed of the plane is 150m/s. Find the directiion in which the pilot should head the plane to reach the point B.

Answer: The vector diagram for various velocities is shown. Vector AC gives velocity of aeroplane relative to quiet air. Vector... View Article

What happens when some charge is placed on a soap bubble? (1) Its radius decreases (2) Its radius increases (3) The bubble collapses (4) None of these

Answer: 2) Its radius increases When the charge is placed on the soap bubble, every partion of the surface of... View Article

When a low flying aircraft passes overhead, we sometimes notice a slight shaking of the picture on our TV screen .This is because of the direct signal and reflected signal (1) Interference (2) Diffraction (3) Polarisation of direct signal (4) Both (b) and (c)

Answer: (1) Interference When a low flying aircraft passes overhead there is a change in magnetic flux and thus it... View Article

On addition of conc.H2SO4 to a chloride salt, colourless fumes are evolved but in case of iodide salt, violet fumes come out. This is because (1) H2SO4 reduces HI to I2 (2) HI is of violet colour (3) HI gets oxidised to I2 (4) HI changes to HIO3

Answer: (3) HI gets oxidised to I2 Because hydrogen iodide is a more powerful reducing agent than sulphuric acid, it... View Article

Two fixed frictionless inclined plane making an angle 30 degree and 60 degree with the vertical are shown below. Two blocks A and B are placed on the two planes. What is the relative vertical acceleration of A with respect to B?

Answer: mg × sinθ = m × a a = g × sinθ Where a is along the inclined plane... View Article

The horizontal range of a projectile fired at an angle of 15° is 50 m. If it is fired with the same speed at an angle of 45°, its range will be (1) 60 m (2) 71 m (3) 100 m (4) 141 m

Answer: (3) 100 m When a particle is thrown obliquely near the earth’s surface, it moves along a curved path... View Article

Glucose on oxidation with bromine water yields gluconic acid. This reaction confirms presence of (1) six carbon atoms linked in straight chain (2) secondary alcoholic group in glucose (3) aldehyde group in glucose (4) primary alcoholic group in glucose

Answer: (3) aldehyde group in glucose Gluconic acid is formed when glucose is oxidised with bromine water. The presence of... View Article

A potentiometer wire of length 100 cm has a resistance of 10 ohm. it is connected in series with a resistance and an accumulator of e.m.f 2 V and of negligible internal resistance . A source of e.m.f. 10 m V is balanced against a length of 40 cm of the potentiometer wire. What is the value of external resistance? (1) 480 ohm (2) 1120 ohm (3) 790 ohm (4) 640 ohm

Answer: (3) 790 ohm Potentiometer is defined as a three-terminal resistor having either sliding or rotating contact that forms an... View Article

A force of 10N acts on a body of mass 2kg for three seconds, initially at rest. Calculate the (1) The velocity acquired by a body (2) Change in momentum of the body

Answer: Push or pull of an object is considered a force. Push and pull come from the objects interacting with... View Article

How to find the factors of 1800?

Answer: Factors of a number are defined as numbers that divide the original number evenly or exactly. The meaning of... View Article

The time period of a freely suspended magnet is 2 sec. If it is broken in length into two equal parts and one part is suspended in the same way, then its time period will be (1) 4sec (2) √2sec (3) 2sec (4) 1sec

Answer: (4) 1sec A bar magnet is a rectangular piece of an object, made up of iron, steel or any... View Article

Under the influence of a uniform magnetic field, a charged particle is moving in a circle of radius R with constant speed v. The time period of the motion (1) depends on v and not on R. (2) depends on both R and v. (3) is independent of both R and v. (4) depends on R and not on v.

Answer: (3) is independent of both R and v. A force acting on a particle is said to perform work... View Article

The electric potential at a certain distance from a point charge is 600 V and the electric field is 200 NC-1. Which of the following statements will be true? (1) The work done in moving a point charge of 1μC from the given point to a point at a distance of 9 m will be 4×10−4 (2) The distance of the given point from the charge is 3 m. (3) The potential at a distance of 9 m will be 200 V. (4) The magnitude of charge is 2×10-3C

Answer: (1), (2) and (3) Electric potential is defined as the amount of work needed to move a unit charge... View Article

If t_n denotes n^th term of the series 2 + 3 + 6 + 11 + 18… ,then t5₀ is (1) 2 + 49² (2) 2 + 48² (3) 2 + 50² (4) 2 + 51²

Answer: (1) 2 + 492 A sequence is an arrangement of any objects or a set of numbers in a... View Article

lf (x + iy)^1/3 = a + ib then x/a+ y/b =? (1) a²− b ² (2) 2(a² −b²) (3) 3(a² − b²) (4) 4(a²− b²)

Answer: (4) 4(a2 – b2) Given (x + iy)1/3 = a + ib (x + iy) = (a + ib)3... View Article

Two masses of 10 kg and 20 kg respectively are connected by a massless spring as shown in figure. A force of 200 N acts on the 20 kg mass at the instant when the 10 kg mass has an acceleration of 12 towards right, the acceleration of the 20 kg mass is (1) m/s² (2) 4m/s² (3) 10m/s² (4) 20m/s²

Answer: (2) 4m/s2 Give m1= 10kg m2 = 20kg F2= 200N a1=12ms−2 a2= ? For mass m1 (10 kg): F... View Article

A bullet fired at an angle of 30 degree with the horizontal hits the ground 3.0 km away. By adjusting its angle of projection, can one hope to hit a target 5.0km away? Assume the muzzle speed to be fixed, and neglect air resistance.

Answer: Given parameters Horizontal range (R) = 3.0km Angle of projection = 30o Acceleration due to gravity (g) = 9.8m/s... View Article

An open vessel at 27^oC is heated until 3/5^th of the air in it has been expelled. Assuming that the volume of the vessel remains constant, find the temperature to which the vessel has been heated?

Answer: According to Charles’ law, when pressure is held constant, the volume of a fixed amount of dry gas is... View Article

If the system of equations 2x + 3y = 7 and 2ax + (a + b)y = 28 has infinitely many solutions, then ______. (1) a = 2b (2) b = 2a (3) a + 2b = 0 (4) 2a + b = 0

Answer: (2) b = 2a Given two equations 2x + 3y = 7 2ax + (a + b)y = 28... View Article

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