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when the densities of the ore particles and gangue particles are different, then the ore is concentrated by

Levigation is based on the difference in densities of the metallic ore and gangue particles. Powdered ore is treated with a stream of running... View Article

an electron in hydrogen like atom is in an excited state. it has a total energy of – 3.4 ev. the de broglie wavelength of the electron is nearly

Energy of electron in hydrogen-like atom, En = −Z^(2)Rhc/n^(2) = −3.4eV Kinetic energy of electron in hydrogen-like atom is equal to negative... View Article

gold (atomic radius= 0.144 nm) crystallises in fcc. the length of a side of the unit cell will be

For a face centred unit cell. r = a/2√2 or a = 2√2r a = 2 × 1.4142 × (0.144nm) = 0.407nm.... View Article

Which of the following has highest bond angle? a) BBr3 b) CS2 c) SO2 d) SF4

a) BBr3 b) CS2 c) SO2 d) SF4 The bond angle around C in CS2 (S=C=S) is 180 degree which is the highest among the given compounds.... View Article

in an adiabatic process, pressure is increased by . if then the volume in the process is decreased by about

For an adiabatic process, pVγ = constant (say C) Here, γ = Cp/CV = 3/2 Therefore, pV^(3/2) = C ⇒ logp + 3/2(logV) = logC ⇒ Δπ/p + 3/2(ΔV/V) = 0... View Article

consider the following reaction at equilibrium pcl5 (g) pcl3 (g) cl2(g). if some amount of argon gas is added to the reaction mixture at constant pressure then

PCl5 (g) ⇔ PCl3 (g) + Cl2(g) The addition of a constant amount of inert gas has no effect on the reaction's equilibrium. This is due to the fact... View Article

Green colour solution is due to the formation

The green colour of the solution is due to the formation of iron sulphate. Metal oxides always reacts with acid to form salt and water. Copper... View Article

Assertion: on reacting with water, calcium starts floating over water. Reason: calcium reacts with cold water at room temperature.

Both the Assertion and Reason are true but Reason is not the correct explanation of the Assertion. Calcium reacts with water, but the reaction... View Article

For which of the following order unit of rate of reaction and rate constant are same? a) First order reaction b) Second order reaction c) Third order reaction d) Zero order reaction

The answer is zero order reaction.For a zero order reaction, Unit of rate = mol/L/tUnit of zero order = mol/L/t... View Article

LCM of 12, 18, 20

Solution: We can find LCM by the prime factorisation method. 12 = 2×2×3 = 22×3 18 = 2×3×3 = 2×32... View Article

The average of four consecutive even numbers is 27. The largest of these numbers is

Solution: Let x-2, x, x+2, x+4 be the four consecutive even numbers. Given that the average of four consecutive even numbers is 27. =>... View Article

The straight line passing through the points (0, 0), (-1, 1) and (1, -1) has equation

(a) 2-x = 3y (b) y = x (c) 2x-y = 0 (d) x+y = 0 Solution: We have to check whether the given points satisfy the equations. Check... View Article

y = x(x-3)² decreases for the values of x given by:

(a) 1<x<3 (b) x<0 (c) x>0 (d) 0<x<3/2 Solution: Given y = x(x-3)2 dy/dx = 2x(x-3) + (x-3)2 = (x-3)(2x + x-3) =... View Article

If [latex]y = tan : x^{tan : x^{tan : x}}[/latex], then dy/dx is

Solution: Given Taking log log y = tan xtan x log (tan x) Taking log log (log y) = log [tan xtan x log (tan x)] = tan x log tan x +... View Article

What is the difference between any 2 consecutive multiples of 17?

Solution: Let x be a multiple of 17. Let the consecutive multiple be x + 17 The difference between any 2 consecutive multiples of 17... View Article

The sum of absolute deviation is least when taken from

(a) mean (b) median (c) mode (d) none of the above Solution: Minimum deviation from mean = ∑|X - mean|/n Minimum deviation from... View Article

The point which lies on the perpendicular bisector of the line segment joining the points A(-2, -5) and B(2, 5) is

(a) (0,0) (b) (0, 2) (c) (2, 0) (d) (-2,0) Solution: A perpendicular bisector of a line segment passes through its... View Article

ABC is a right-angled triangle right angled at B such that BC = 6 cm and AB = 8 cm. A circle with center O is inscribed in triangle ABC. The radius of the circle is

(a) 1 cm (b) 2 cm (c) 3 cm (d) 4 cm Solution: Given BC = 6 cm and AB = 8 cm By using Pythagoras Theorem, we can find AC. AC2 = BC2 + AB2... View Article

The differential coefficient of sec (tan^-1x)

Solution: We have to find the derivative of sec(tan-1x). Let y = sec(tan-1x) We know derivative of sec x = sec x tan x Derivative of... View Article

Three coins are tossed at once. What is the probability of two heads and one tail?

Solution: Probability is a branch of mathematics that deals with the occurrence of a random event. For example, when a coin is tossed in the... View Article

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