The half-life of Au198 is 2.7 days. The activity of 1.50 mg of Au198 if its atomic weight is 198 g mol-1 is (NA = 6 × 1023/mol).
a. 252 Ci b. 357 Ci c. 240 Ci d. 535 Ci Answer: (b) Initial activity = Ao = λNo... View Article
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The magnetic field in a region
The magnetic field in a region is given by \(\begin{array}{l}\vec{B} = B_{o}\left ( \frac{x}{a} \right )\hat{k}\end{array} \). A square loop... View Article
Two identical antennas mounted on identical towers are separated from each other by a distance of 45 km. What should nearly be the minimum height of the receiving antenna to receive the signals in line of sight? (Assume radius of earth is 6400 km)
a. 19.77 m b. 79.1 m c. 158.2 m d. 39.55 m Answer: (d) D = 2√2Rh \(\begin{array}{l}H = \frac{D^{2}}{8R}... View Article
The following logic gate is equivalent to:
The following logic gate is equivalent to: a. NOR Gate b. AND Gate c. OR Gate d. NAND Gate Answer:... View Article
A bimetallic strip consists of metals A and B.
A bimetallic strip consists of metals A and B. It is mounted rigidly as shown. The metal A has higher... View Article
Calculate the value of mean free path (λ) for oxygen molecules at temperature 27°C and pressure 1.01 × 105 Pa. Assume the molecular diameter 0.3nm and the gas is ideal. (k = 1.38 × 10-23 jK-1)
a. 102 nm b. 32 nm c. 58 nm d. 86 nm Answer: (a) Given: P = 1.01 × 105... View Article
A resistor develops 500 J of thermal energy in 20s when a current of 1.5A is passed through it. If the current is increased from 1.5A to 3A, what will be the energy developed in the 20s.
a. 500 J b. 1000 J c. 2000 J d. 1500 J Answer: (c) I2RT= H \(\begin{array}{l}\frac{H_{1}}{H_{2}} = \left (... View Article
Amplitude of a mass spring system, which is executing simple harmonic motion decreases with time. If mass = 500g, Decay constant = 20 g/s then how much time is required for the amplitude of the system to drop to half of its initial value?
(ln 2 = 0.693) a. 15.01 s b. 17.32 s c. 0.034 s d. 34.65 s Answer: (d) \(\begin{array}{l}A =... View Article
A charge Q is moving [latex]vec{dl}[/latex] distance in the magnetic field [latex]vec{B}[/latex]. Find the value of work done by [latex]vec{B}[/latex].
a. Infinite b. 1 c. –1 d. Zero Answer: (d) \(\begin{array}{l}\vec{F}= q(\vec{V}\times \vec{B})\end{array} \); Since force F on a point... View Article
The de-Broglie wavelength associated
The de-Broglie wavelength associated with an electron and a proton were calculated by accelerating them through the same potential of... View Article
Red light differs from blue light as they have:
a. Same frequencies and same wavelengths b. Different frequencies and different wavelengths c. Different frequencies and same wavelengths d. Same... View Article
For the given circuit, comment on the type of transformer used.
For the given circuit, comment on the type of transformer used. a. Step down transformer b. Auxiliary transformer c. Step-up... View Article
The refractive index of a converging lens is 1.4. What will be the focal length of this lens if it is placed in a medium of the same refractive index? Assume the radii of curvature of the faces of the lens are R1 and R2 respectively.
a. Zero b. \(\begin{array}{l}\frac{R_{1}R_{2}}{R_{1}-R_{2}}\end{array} \) c. Infinite d. 1 Answer: (c) \(\begin{array}{l}\frac{1}{f}=\left [ \frac{n_{2}}{n_{1}}-1 \right ]\left [ \frac{1}{R_{1}}-\frac{1}{R_{2}} \right ]\end{array}... View Article
What will be the nature of the flow of water from a circular tap, when its flow rate increased from 0.18 L/min to 0.48 L/min? The radius of the tap and viscosity of water is 0.5 cm and 10-3 Pa s, respectively. (Density of water: 103 kg/m3)
a. Remains steady flow b. Unsteady to steady flow c. Steady flow to unsteady flow d. Remains turbulent flow Answer:... View Article
A large block of wood of mass
A large block of wood of mass M = 5.99 kg is hanging from two long massless cords. A bullet... View Article
Calculate the time interval between 33% decay and 67%decay if half-life of a substance is 20 minutes
Calculate the time interval between 33% decay and 67%decay if half-life of a substance is 20 minutes: a. 40 minutes... View Article
A cyclist is moving on an unbanked road
Statement I: A cyclist is moving on an unbanked road with a speed of 7 kmh-1 and takes a sharp... View Article
A mosquito is moving with a velocity [latex]vec{v} = 0.5t^{2}hat{i} + 3that{j} + 9hat{k}[/latex] m/s and accelerating in uniform conditions. What will be the direction of the mosquito after 2s?
a. tan-1 (⅔) from x – axis b. tan-1 (5/2) from x – axis c. tan-1 (⅔) from y – axis d. tan-1 (5/2) from y –... View Article
Complete combustion of 3 g of ethane gives x × 1022 molecules of water. The value of x is
Complete combustion of 3 g of ethane gives x × 1022 molecules of water. The value of x is ________.... View Article
In order to prepare a buffer solution of pH 5.74, sodium acetate is added to acetic acid.
In order to prepare a buffer solution of pH 5.74, sodium acetate is added to acetic acid. If the concentration... View Article
