Dyeing MCQs (Set-4)

From an initial exhaust recipe, 87.5% of dye leaves the bath and 80% of exhausted dye remains fixed after wash-off. What fraction of initial dye is fixed?

Scattering differs materially between two dyed textiles. Why can their K/S values alone fail to show which holds more dye?

Combine two stocks of 12 g/L and 3 g/L to make 900 mL at 8 g/L. Assuming additive volumes, how much stronger stock is needed?

Equilibrium uptake approaches a plateau as bath concentration increases. What can explain this in a finite-site model?

On a pad line, 150 kg/h of dry fabric retains 0.70 L per kilogram. At 12 g/L dye, what application rate follows?

Temperature and salt level changed together and exhaustion improved. Which design separates factors?

Wash liquor originally contains no dye. It finishes at 0.22 g/L in 250 L. What percentage of a 200 g original on-fibre load was washed off?

Under a dilute linear colour-strength model with unchanged scattering, what happens to relative strength when retained dye is doubled?

In a first-order uptake model, half the distance to equilibrium remains after one interval. What percentage remains after three equal intervals?

Formulation X yields 12 g wash-off from 800 g on fibre. Formulation Y yields 9 g wash-off from 450 g on fibre. Which has lower proportional loss?

A continuous bath contains 400 L and is replenished at 20 L/min by liquor at 3 g/L. At a moment when carryout is 20 L/min at 2 g/L, what is the net dye accumulation if other losses are negligible?

Given a partition isotherm C_f = 4 C_b with coefficient 4 mL/g, what fibre concentration follows from a 0.15 mg/mL equilibrium bath concentration?

Under a diffusion model with penetration depth proportional to the square root of elapsed time, what total time is needed to double depth?

Using the model K/S = (1 − R)²/(2R), what is K/S when R = 0.20?

Each drain removes 25% of the bath dye then present. After two drains with a dye-free refill in between, how much original bath dye remains?

Before wash-off, the textile carries 600 g of dye. Exhaustion was 80% and other losses were negligible. What mass was initially dosed?

At a selected wavelength, dye X and dye Y both absorb. Why is one uncorrected absorbance reading generally insufficient to determine both bath concentrations?

Suppose half of the applied dye is at the surface and half is internal. Wash-off removes 40% of the surface dye only. What fraction of all applied dye remains?

Blend component masses are 40 kg polyester and 60 kg cotton. Their dye uptakes are 2% and 1% of respective masses. What is total uptake?

At startup, 400 kg of goods must be dyed at 2% owf. What volume of 40 g/L stock supplies enough dye?

Under the same dye concentration gradient across equal fibre paths, the dye diffusion coefficient in one polymer is half that in the other. What is the diffusion flux ratio, slower to faster, under Fick’s first law?

Production substitutes a dye with better fixation but the same exhaustion. Assuming equal initial dosage, which loss can fall most directly?

Change a bath from 10 L/kg to 4 L/kg while holding the dye dose at 20 g per kilogram of goods. How many grams per litre are needed in the smaller bath?

To improve levelness without changing dye strength, a lab extends the period of low-temperature circulation before fixation. Which finding would support successful redistribution?

A padding line gives 1.8 g of dye per metre at the current speed. To keep the same dye per metre when fabric speed doubles, how must liquor carryout per minute change if concentration stays fixed?