Chemical Engineering Archives

7621. A solid is being dried in the linear drying rate regime from moisture content Xo to XF. The drying rate is zero at X = 0 and the critical moisture content is the same as the initial moisture Xo. The drying time for M = (Ls/ARc) is (where, L = total mass of dry solid, A = total surface area for drying Rc = Constant maximum drying rate per unit area X = moisture content (in mass of water/mass of dry solids)

M(Xo – XF)

M(Xo/XF)

M ln(Xo/XF)

MXo ln(Xo/XF)

✅ The correct answer is option D.

7622. An irreversible first order reaction is being carried out in a CSTR and PFR of same volume. The liquid flow rates are same. The relative conversion will

Be more in CSTR than in PFR

Be more in PFR than in CSTR

Be same in both cases

Depend on the temperature

✅ The correct answer is option B.

7623. The ‘shanks system’ of leaching (i.e., counter-current multiple contact leaching) is used for

Recovery of tannis from the tree barks and woods

Leaching sodium nitrate from Chilean nitrate bearing rock

Both A & B

Neither A nor B

✅ The correct answer is option C.

7624. A trickle bed reactor is the one, which

Has altogether three streams either entering or leaving

Processes three reactants at different flow rates

Processes three reactants with same flow rate

Employs all the three phases (i.e.. .solid, liquid and gas)

✅ The correct answer is option D.

7625. The diffusivity, DAB (for component A diffusing in B) is equal to the diffusivity Dsub>BA (for component B diffusing in A) for a binary mixture of

Newtonion liquids

Non-Newtonion liquids

Ideal gases

Real gases

✅ The correct answer is option C.

7626. For an ideal mixed flow reactor (CSTR), the exit age distribution E(t) is given by

A dirac delta function

A step function

A ramp function

None of the above

✅ The correct answer is option D.

7627. Organic catalysts differ from the inorganic catalyst in the sense that the former is

Active at cryogenic temperatures only

Prohibitively costly

Proteinous in nature

Active at very high temperature only

✅ The correct answer is option C.

7628. For all positive reaction orders for a particular duty,

Mixed reactor is always larger than the plug-flow reactor

Ratio of the volume of the mixed reactor to that of the plug-flow reactor decreases with order

Reactor size is independent of the type of flow

Density variation during reaction affects design

✅ The correct answer is option A.

7629. Half life period of decomposition of a liquid ‘A’ by irreversible first order reaction is 12 minutes. The time required for 75% conversion of ‘A’ is __________ minutes.

✅ The correct answer is option B.

7630. Find a mechanism that is consistent with the rate equation and reaction given below: 2A + B → A₂B, ( – rA) = k.CA.CB

A + B ⇋ AB ; AB + A → A2B

A + B → AB ; AB + A → A2B

A + A → AA ; AA + B → A2B

A + A ⇋ AA ; AA + B → A2B

✅ The correct answer is option D.