Description : For an ideal black body (A) Absorptivity = 1 (B) Reflectivity = 1 (C) Emissivity = 0 (D) Transmissivity = 1
Last Answer : (A) Absorptivity = 1
Description : The sum of reflectivity and absorptivity for an opaque body is equal to (A) 0.5 (B) 1 (C) 0 (D) 2
Last Answer : (B) 1
Description : For a perfectly transparent surface (like gases), the (A) Absorptivity = 0 (B) Transmissivity = 1 (C) Reflectivity = 0
Last Answer : (B) Transmissivity = 1
Description : Define the following terms : (i) absorptivity (ii) reflectivity (iii) transmissivity (iv) emissivity
Last Answer : Absorptivity: It is the fraction of total incident radiation which is absorbed by a body. Reflectivity: It is the fraction of total incident radiation which is reflected by a body. Transmissivity: It ... total emissive power of a body to emissive power of a black body at the same temperature.
Description : Absorptivity of a perfect black body is unity. Which of the following has maximum absorptivity? (A) Aluminium foil (B) Refractory bricks (C) Iron plate (D) Coke breeze
Last Answer : (D) Coke breeze
Description : What is the absorptivity of a black body? (A) 1 (B) 0 (C) 0.78 (D) 0.95
Last Answer : (A) 1
Description : What is the absorptivity of a black body? A. 0 B. 1 C. 0.5 D. 0.25
Last Answer : 1
Description : Define: i. Transmissivity ii. Black body iii. Grey body iv. Reflectivity
Last Answer : Transmissivity: It is the the fraction of energy which is transmitted through the body. Or The ratio of amount of energy transmitted to the amount of energy incident on a body. Black body: A ... is defined as the ratio of amount of energy reflected to the amount of energy incident on a body.
Description : In thermal radiation for a black body (where, ε is emissivity and α is absorptivity) (A) α = 1; ε ≠ 1 (B) α ≠ 1, ε = 1 (C) α ≠ 1, ε ≠ 1 (D) α = 1; ε = 1
Last Answer : (D) α = 1; ε = 1
Description : Pick out the wrong statement: (A) With change in temperature, the radiant energy emitted by a black body remains unchanged (B) Absorptivity of a body approaches unity in case of diffuse reflection (C) Absorptivity of ... unity (D) Value of Stefan-Boltzmann constant is 4.876 10 -8 KCal/m2 .hr.°K4
Last Answer : (A) With change in temperature, the radiant energy emitted by a black body remains unchanged
Description : What is the thermal conductivity of a perfect heat insulator? (A) Zero (B) One (C) ∞ (D) Between 0 and ∞
Last Answer : (A) Zero
Description : The ratio of total radiating power to the absorptivity of the body depends upon the __________ as per Kirchoff’s law. (A) Wavelength of radiation (B) Nature of the body (C) Temperature of the body (D) None of these
Last Answer : (C) Temperature of the body
Description : The absorptivity of a body is equal to its emissivity (A) At a particular temperature (B) For circular bodies (C) Under thermal equilibrium (D) None of these
Last Answer : (C) Under thermal equilibrium
Description : The absorptivity of a grey body at a given temperature __________ with increasing wavelength of radiation. (A) Increases (B) Decreases (C) Remain constant (D) May increase or decrease; depends on the material
Last Answer : (D) May increase or decrease; depends on the material
Description : What refers to the rate of thermal radiation emitter per unit area of a body? A. Thermal conductivity B. Absorptivity C. Emissivity D. Emissive power
Last Answer : Emissive power
Description : The changes in the reflectivity/emissivity with time, is called: (A) Spectral variation (B) Spatial variation (C) Temporal variation (D) None of these
Last Answer : Answer: Option C
Description : A reduction of nitrogen nutrient in plants: (A) Affects leaf colour (B) Reduces pigment concentration (C) Increase the visible reflectivity (D) All of these
Last Answer : Answer: Option D
Description : Which one of the following is not a matter a global concern in the removal of tropical forests ? (A) Their ability to absorb the chemicals that contribute to depletion of ozone layer ... , moisture content and reflectivity. (D) Their contribution to the biological diversity of the planet.
Last Answer : (A) Their ability to absorb the chemicals that contribute to depletion of ozone layer.
Description : Which of the following has the minimum absorptivity? (A) Aluminium foil (B) Coal dust (C) Refractory bricks (D) Iron plates
Last Answer : (A) Aluminium foil
Description : The ratio of the total emissive power to the absorptivity for all bodies is same at ther-mal equilibrium". This is __________ law. (A) Kirchoff’s (B) Planck's (C) Wien's displacement (D) Stefan-Boltzmann
Last Answer : (A) Kirchoff’s
Description : While the total emissivity of a perfect black body is unity, the same for a real body is (A) 0 (B) 1 (C) > 1 (D) Between 0 and 1
Last Answer : (D) Between 0 and 1
Description : What states that for any two bodies in thermal equilibrium, the ratios of emissive power to the absorptivity are equal? A. Kirchhoff’s radiation law B. Newton’s law of cooling C. Stefan-Boltzmann law D. Hess’s law
Last Answer : Kirchhoff’s radiation law
Description : What is the selectivity index, if the grade of tailings & concentrate is the same? (A) 0 (B) ∞ (C) 1 (D) 0.5
Last Answer : (C) 1
Description : The value of NA/(NA + NB), for steady state equimolal counter diffusion of two gases 'A' and 'B' is (A) 1 (B) ∞ (C) 0.5
Last Answer : (B) ∞
Description : The value of NA/(NA + NB) for steady state molecular diffusion of gas 'A' through non-diffusing gas 'B' is (A) 1 (B) ∞ (C) 0.5 (D) 2
Description : For an incompressible fluid, the bulk modulus of elasticity is (A) 5 kg/m3 (B) ∞ N/m2 (C) 1 N (D) 0 N/m
Last Answer : (B) ∞ N/m2
Description : Colebrook equation for friction factor in turbulent flow is given by, f -0.5 = -4 loge [(ε/D) + (1.26/NRe √F). It reduces to Nikuradse equation for a value of (ϵ/D) equal to (A) 0 (B) 1 (C) ∞ (D) 0.5
Description : If Thiele modulus is __________, then the pore diffusion resistance in a catalyst may be considered as negligible. (A) 0 (B) ∞ (C) < 0.5 (D) > 0.5
Last Answer : (C) < 0.5
Description : Cetane number of alpha methyl naphthalene is assumed to be (A) 0 (B) 100 (C) 50 (D) ∞
Last Answer : (A) 0
Description : Octane number of n-heptane is assumed to be (A) 100 (B) 0 (C) 70 (D) ∞
Last Answer : (B) 0
Description : Compressibility co-efficient for an absolutely compressible cake is (A) 0 (B) 1 (C) 0 to 1 (D) ∞
Description : At what value of reflux ratio, number of theoretical plates in a distillation column is minimum? (A) 0 (B) 1 (C) ∞ (D) < 1
Last Answer : (C) ∞
Description : At the boiling point of the liquid at the prevailing pressure, the saturated absolute humidity becomes (A) 1 (B) 0 (C) ∞ (D) None of these
Description : The slope of the operating line for a single component co-current absorber when plotted in terms of mole ratio units is (A) 0 (B) ∞ (C) -ve (D) +ve
Last Answer : (C) -ve
Description : The relative volatility of a binary mixture at the Azeotropic composition is (A) 1 (B) > 1 (C) 0 (D) ∞
Last Answer : (D) ∞
Description : In a 1-1 concurrent heat exchanger, if the tube side fluid outlet temperature is equal to the shell side fluid outlet temperature, then the LMTD is (A) ∞ (B) 0 ... temperature (D) Equal to the difference between hot fluid inlet temperature and cold fluid outlet temperature
Description : For an ideal fluid flow, Reynolds number is (A) 2100 (B) 100 (C) 0 (D) ∞
Description : The ratio of volume of mixed reactor to the volume of P.F.R. (for identical flow rate, feed composition and conversion) for zero order reaction is: (A) ∞ (B) 0 (C) 1 (D) > 1
Description : For an ideal plug flow reactor, the value of Peclet number is (A) 0 (B) 1 (C) 10 (D) ∞
Description : The eddy diffusivity for a liquid in plug flow must be (A) 1 (B) 0 (C) ∞ (D) Between 0 and 1
Description : What is the dispersion number for a plug flow reactor? (A) 0 (B) ∞ (C) 1 (D) -1
Description : The vessel dispersion number (D/μL) for plug flow is (A) 0 (B) 500 (C) 750 (D) ∞
Description : What is the dispersion number for a CSTR? (A) 0 (B) 1 (C) < 1 (D) ∞
Description : The exit age distribution of a fluid leaving a vessel (denoted by E) is used to study the extent of non-ideal flow in the vessel. The value of ∫∞ 0 E.dt is (A) 0 (B) 1 (C) ∞ (D) √2π
Description : The Joule-Thomson co-efficient is defined as (∂T/∂P)H. Its value at the inversion point is (A) ∞ (B) 1 (C) 0 (D) -ve
Last Answer : (C) 0
Description : The difference between isothermal compressibility and adiabatic compressibility for an ideal gas is (A) 0 (B) +ve (C) -ve (D) ∞
Last Answer : (B) +ve
Description : 4 kg moles of an ideal gas expands in vacuum spontaneously. The work done is (A) 4 J (B) ∞ (C) 0 (D) 8 J
Description : Entropy change for an irreversible isolated system is (A) ∞ (B) 0 (C) < 0 (D) > 0
Last Answer : (D) > 0
Description : Joule-Thomson Co-efficient at any point on the inversion curve is (A) ∞ (B) +ve (C) 0 (D) -ve
Description : Gibbs free energy at constant pressure and temperature under equilibrium conditions is (A) ∞ (B) 0 (C) Maximum (D) Minimum
Last Answer : (D) Minimum