List of top Questions asked in OJEE

A metal ball of radius 0.1m at a uniform temperature of 900°C is left in air at 300°C. The density and the specific heat of the metal are 3000 kg/m³ and 0.4 kJ/kg·K. The heat transfer coefficient is 50 W/m²·K. Neglecting the temperature gradient inside the ball, the time taken (in hours) for the ball to cool to 600°C is

A beam is a structural member which is subjected to

In a simply supported beam, bending moment at the end

Point of contra-flexure is a

The relationship between Young’s modulus (E), Bulk modulus (K) and Poisson’s ratio ($\mu$) is given by

Mohr’s circle is a graphical method to find

Which of the following solvents has maximum distribution coefficient at 200°C for the extraction of acetic acid from acetic acid – water system?

A process stream of dilute aqueous solution flowing at the rate of 10 kg/s is to be heated. Steam condensate at 95°C is available for heating purpose, also at a rate of 10 kg/s. A 1-1 shell and tube heat exchanger is available. The best arrangement is

A pure drug is administered as a sphere and as a cube. The amount of drug is the same in the two tablets. Assuming that the shape and size do not influence the mass transfer, the ratio of rate of dissolution in water at t=0 for the cubic to spherical tablet is

In a distillation operation, what is the effect of the temperature of the reflux stream (given below) on the condenser and reboiler loads? Reflux conditions - Reflux stream is completely liquid and is at its bubble point - Reflux stream is below its bubble point

Gilliland’s equation and Underwood’s equation are used for the calculation of

A filter cake is dried with air at wet and dry bulb temperatures of 300K and 323K. The heat transfer coefficient is 11W/m\(^2\)K and the latent heat of vaporization of water is 2500 KJ/Kg. Mass transfer does not limit the process. Select the drying rate during constant rate period. Neglect conduction through the solid and radiation effects.

The McCabe $\Delta$L law states that the

Compound A is extracted from a solution of A + B into a pure solvent S. A co-current unit is used for the liquid-liquid extraction. The inlet rate of the solution containing A is 200 mol of B/h-m\(^2\) and the solvent flow rate is 400 mol of S/h-m\(^2\). The equilibrium data is represented by \( Y = 3X^2 + 0.3088 \), where Y is in mol of A/mol of B and X is in mol of A/mol of S. The maximum percentage extraction achieved in the unit is

The Grashof number is the ratio of

Two reactors with average residence times \( t_1 \) and \( t_2 \) are placed in series. Reactor 1 has zero dispersion and reactor 2 has infinite dispersion. The E curve of the system is given by

A batch adiabatic reactor at an initial temperature of 373K is being used for the reaction A to B. Assume the heat of reaction to be -1 kJ/mol at 373K and the heat capacity of both A and B to be constant and equal to 50J/mol-K. The temperature rise after a conversion of 0.5 will be

A pulse tracer is introduced in an ideal CSTR (with a mean residence time of \( t \)) at time = 0. The time taken for the exit concentration of the tracer to reach half of its initial value will be

For a gas phase reaction, A + 3B = 2C, if some inerts are added into the system under otherwise uniform conditions, conversion of A will

Thiele modulus is not a function of initial concentration for which of the following order reactions

A batch distillation operation is carried out to separate a feed containing 100 mol of a binary mixture of A and B. The mole fraction of A in the feed is 0.7. The distillation progresses until the mole fraction of A in the residue decreases to 0.6. The equilibrium curve in this composition range may be linearized to \( y = 0.7353x + 0.3088 \). Here, \( x \) and \( y \) are the mole fractions of the more volatile component A in the liquid and vapor phases. The number of moles of residue is

Maximum energy per gram on oxidation is yielded from

Which of the following promotes branch migration at higher rates than does Rec-A?

Site directed mutagenesis facilitated research on

For a first order isothermal catalytic reaction A to B, occurring in an infinitely long cylindrical pore, the relationship between effectiveness factor \(\epsilon\) and thiele modulus \(\phi\), is