Explore topic-wise InterviewSolutions in .

Correct answer is (a) True

Explanation: At saturation point, a dynamic equilibrium is established between the two processes of dissolution and crystallization. These reactions occur at the same rate. When more solute is added beyond saturation point, dissolution of solute TAKES PLACE but same amount of solute recrystallizes at the same rate. HENCE MAKING it look like dissolution does not occur when it actually does.

Right option is (d) PPB

Easiest explanation: DRINKING water should be absolutely clean from all sorts of toxic, hazardous elements. Trace quantities may cay cause POISONING in the human body. Universally, it has been considered APPROPRIATE to express lead concentrations in ppb (parts per billion) for drinking water.

The correct ANSWER is (d) Solid foam

The explanation: There are 8 types of colloidal solutions namely solid SOL, sol, solid aerosol, gel, EMULSION, liquid aerosol, solid foam and foam. Pumice STONE is a gas in solid type colloidal solution, i.e., solid foam.

Correct choice is (c) Polar

Explanation: Water is a universal solvent. It has the ability to dissolve the greatest number of SUBSTANCES than any other solvent. The highly polar nature accounts for this special feature as the water molecule BEARS a slightly positively CHARGED hydrogen ion and two highly negatively charged oxygen IONS. Since, it becomes attracted to many different types of molecules it is known as the ‘universal solvent’.

The correct option is (a) Henry’s LAW

To explain I would SAY: Henry’s law states that the partial pressure of a gas in VAPOR phase varies directly with its mole fraction in the solution. At higher altitudes the partial pressure of O2 decreases HENCE the decrease in its concentration which causes difficulty in breathing.

The correct ANSWER is (d) 0.0067

The explanation: Given,

Normality, N = 0.02

It is known that N = nf x M, where nf is the n-factor of equivalence and M is the molarity of the solution.

On expanding, N = nf x \(\frac{Number \, of \, moles}{VOLUME \, of \, solution(L)}\)

For H3PO4, nf = 3 since there are 3 breakable OH bonds.

Therefore, N = 3 x \(\frac{Number \, of \, moles}{mass \, of \, solvent(kg)}\) . Here, volume of solution (1 L) can be approximated as mass of solvent (1 kg) since it is an dilute solution in water (density = 1 kg/L) implying water concentration is far greater such that amount of H3PO4 is negligible.

Now, \(\frac{Number \, of \, moles}{mass \, of \, solvent(kg)}\) = molality of solution

Thus, N/3 = 0.02/3 =0.0067 MOLAL.

Correct answer is (B) Element

To explain: A solution is made up of two parts, the solute and the solvent. Solvent is present in larger quantity which DISSOLVES a solute. The process of dissolution involves formation of homogeneous bonds between the particles of solvent and solute. E.g. SALT-WATER solution is made by DISSOLVING salt, NaCl (solute) in water (solvent).

Right OPTION is (a) Solubility

Explanation: Solubility is the maximum amount of SOLUTE that can be dissolved in a given solvent at a particular TEMPERATURE and pressure. It is usually expressed in grams of solute dissolved in 100 grams of the solvent. Any more solute added beyond this forms a SUPERSATURATED solution as none of the PARTICLES dissolve any more.

Correct option is (b) 11.9

Easy explanation: 98% (v/v) means 98 mL of acid is present in 100 mL of solution.

In 650 mL of solution, volume of acid present = 0.98 x 650 mL = 637 mL

Mass of acid present = volume x density = 637 mL x 1.83 g/mL =1165.71 g

Molar mass of sulfuric acid (H2SO4) = (2 x 1 + 32 + 4 x 16) = 98 g/mole

Number of MOLES of sulfuric acid = mass/molar mass = 1165.71g/(98 g/mole) = 11.9 moles.

The correct option is (c) Brass

To elaborate: An alloy of COPPER and zinc is called Brass. German silver is an alloy of copper, zinc and nickel, sometimes also CONTAINING LEAD and tin. Bronze is an alloy of copper and tin. Solder is an alloy of tin, lead and antimony.

Correct choice is (b) Argon is less SOLUBLE than CO2

The best explanation: Henry’s law is formulated ASP = KH x X (mole fraction). From this, it is seen that as KH increases, mole fraction decreases in order to compensate the INCREASE in partial pressure of the gas. Hence, higher the KH value lower is the solubility. Therefore, argon is less soluble in water than CO2 at 298 K.

Right answer is (d) Positive deviation from Raoult’s law

Explanation: Deviation is always exhibited by NON-solutions. Non- ideal solutions do not obey Raoult’s behavior. This is because ΔHmix, ΔVmix ≠ 0. The cause for this is the INTERMOLECULAR attractions. In this CASE, molecular attraction between A – B is weaker than that of A – A and B – B. Hence the easier it is to break the bonds and BOIL faster at a lower temperature than that of either of A and B.

The correct CHOICE is (a) Boiling

The explanation: Boiling, by definition, occurs when the vapor pressure of a liquid equals the SURROUNDING ATMOSPHERIC pressure. It is a very quick VAPORIZATION PROCESS which takes place at a constant temperature, referred to as the boiling point.

Correct ANSWER is (d) [Ag^+]^2 [CrO4^2-]^2

Explanation: The FORMULA for silver chromate is Ag2CrO4. On the other hand, silver dichromate is formulated as Ag2Cr2O7. If a COMPOUND is represented as AXBY then the solubility product expression is written in terms of its MOLAR concentration as [A^+]^X [B^–]^Y. Similarly, the solubility product expression for Ag2CrO4 is GIVEN as [Ag^+]^2 [CrO4^2-]^2.

Right option is (d) 2.04 M

The BEST I can EXPLAIN: Given,

20% (w/v) means 20 g of H2SO4 is present in 100 mL (= 0.1L) of solution.

Data –

Moles of SOLUTE (H2SO4) = mass of solute/molar mass

Moles of solute, n = 20 g/(2 x 1 + 32 + 4 x 16) g/mole = 0.204 mole

Volume, V = 0.1 L

Molarity, M = moles of solute (n)/volume of solution (V)

M = 0.204 moles/0.1 L = 0.204 M.

The correct answer is (C) Solid in gas solution

Easy explanation: CAMPHOR in N2 gas is an EXAMPLE of solid in gas gaseous solution. A solution in which the solvent is gaseous is called gaseous solution. Some other examples of gaseous solutions are air (O2 + N2), IODINE vapours in air, HUMIDITY in air, etc.

Correct choice is (c) Dalton’s law

Easiest EXPLANATION: Dalton’s of partial pressure states that for a non-reactive mixture of gases in a closed VESSEL, the total pressure of the mixture is the sum of PRESSURES all INDIVIDUAL gas components present. If gases A, B and C are present then, total pressure, Ptotal = PA + PB + PC.

Correct answer is (B) Molality

The explanation: Molality gives the more accurate READING since it is a temperature INDEPENDENT term. On the other hand, the other terms are temperature DEPENDENT since they make use of volume of solution, which TENDS to change with changing temperatures.

The correct choice is (a) 0.008%

Best explanation: 80 ppm silica MEANS there are 80 mg of silica is 10^6 mg (or 1 kg) of iron (III) oxide and silica mixture. The mixture can be regarded as 10^6 mg (or 1 kg) of iron (III) oxide since 80<<10^6

MASS% = (mass of impurity/mass of total mixture) X 100%

Mass% = (80mg/10^6mg) x 100% = 0.008%.

Correct choice is (B) Solid sol

To elaborate: Emulsion, solid sol, solid aerosol and gel are types of colloidal SOLUTIONS. CRANBERRY glass is formed by the addition of a solid solute to a solid solvent(gold SALTS and glass respectively). HENCE, it is a Solid sol.

The CORRECT ANSWER is (d) Aerated drinks

Best explanation: A SOLID solution is a solid-state solution of one or more solutes in a solvent. Brass, bronze, and hydrated SALTS are examples of solid solutions. Aerated drinks are examples of liquid solutions (GAS in liquid).

The correct answer is (b) 15.082 kPa

Easy EXPLANATION: GIVEN,

P^0eth = 5.95 kPa

P^0chl = 21.17 kPa

Mole ratio of ethanol ∶ CHLOROFORM = 2 ∶ 3

Total number of parts = 2 + 3 = 5

Therefore, mole fraction of ethanol, Xeth = 2/5 = 0.4

Mole fraction of chloroform, Xchl = 3/5 = 0.6

From Raoult’s law, pA = p^0A X XA

Peth = 5.95 x 0.4 = 2.38 kPa

Pchl = 21.17 x 0.6 = 12.702 kPa

From Dalton’s law, Ptotal = Peth + Pchl

Ptotal = 2.38 + 12.702 = 15.082 kPa.

Right answer is (b) Molality

To elaborate: The base of calculating molality of a solution is FINDING out the number of MOLES of solute per KG of solvent. Molarity is the number of moles o solute present per unit volume of solution, in liters. Molar mass refers to the mass of substance CONSTITUTING one mole. Milli-molarity refers to number of milli-moles of solute present per unit volume of solution, in liters.

Correct option is (b) m

Easiest explanation: UNIVERSALLY, ‘m’ is used to denote molality concentrations. E.g. 2 m means a SOLUTION having concentration 2 molal (2 moles of solute/kg solvent). ‘M’ is used to molarity. E.g. 2 M means a solution having concentration 2 MOLAR (2 moles of solute/L solution). ‘mM’ corresponds to milli-molar concentration and ‘n’ DENOTES number of moles of a component.

Correct answer is (d) The solute precipitates out of the solution

For EXPLANATION: When a solute crystal is added to a supersaturated solution, solute particles LEAVE the solution and forms a crystalline precipitate. The ADDITION of the solute crystal is also called seeding.

Correct choice is (c) 0.205

Best explanation: Mw of glycerin = 92g/mol. Number of moles of glycerin = 33/92 = 0.3587 mol

Number of moles of isopropyl ALCOHOL = 60G/(60g/mole) = 1 mole

Number of moles of WATER = 7g/(18g/mole) = 0.3889 mole

Mole fraction of glycerin = 0.3587/(0.3587 + 1 + 0.3889) = 0.205.

Correct ANSWER is (a) Reduction in equilibrium of vapor pressure of solution

Explanation: This PHENOMENON is known as ‘relative LOWERING of vapor pressure’ which is a very common colligative property. When a non-volatile SOLUTE is ADDED to a solvent, the upper surface of the solvent is covered partially. Hence, the solvent molecules do not bear maximum freedom to escape into the space as vapors. Consequently, there is a decrease in vapor pressure when compared towhat it would have been with pure solvent and no solute at all.

The correct option is (B) 4.878 N

For explanation: CONSIDER 100g of solution. It is made up of 26g lead (II) NITRATE and 74g water.

Volume of solution, V = 100g/(3.105g/ml) = 32.2061 ml = 0.0322 L

Equivalent weight of lead nitrate = 331/2 = 165.5 g/eq

Number of equivalents, N = 26g/(165.5g/eq) = 0.1571 eq

Normality = N/V = 4.878 N.

The CORRECT answer is (b) 250 PPM

The explanation is: ppm = (mass of SOLUTE/mass of solution) X 10^6

Mass of solute = 0.025 g

Mass of solution = 0.025 + 100 = 100.025 g

Concentration in ppm = (0.025/100.025) x 10^6 = 250 ppm.

Correct option is (b) Stainless steel

Best explanation: BRONZE is an alloy of copper and tin. Stainless steel is an alloy of iron with CHROMIUM. It ALSO contains varying amounts of carbon, silicon and manganese. Brass is an alloy of copper and ZINC. Gunmetal is an alloy of copper, tin and zinc.

Correct option is (c) Decreases with increasing temperature

Explanation: In an equilibrium system of gas dissolved in solvent, when pressure over it is INCREASED more and more gas particles are forced into a smaller volume. This also increases the rate at which they strike the surface of the solvent to enter it. Consequently, more gas dissolves with increasing pressure. In the case of increasing temperature, gas particles gain SUFFICIENT energy to escape the solvent and SOLUBILITY decreases.

The correct answer is (b) 96.4 KG

Explanation: Let us consider 100 kg sample or urea. This is said to contain 45kg N2.

Now, 60kg urea contains 28 kg N2. (Since, Mw of urea = 14 + 2 + 12 + 16 + 14 + 2 = 60kg/kmole)

Then, 1kg urea contains \(\FRAC{28}{60}\)kg N2.

Using unitary method, x kg urea will contain 45 kg N2.

Solving for x –

x= 45 x \(\frac{60}{28}\) = 96.4 kg.

The CORRECT option is (a) True

Easy explanation: Alloys of mercury with other METALS are called amalgams. An alloy is a type of solid solution (solid in solid). Some IMPORTANT amalgams are zinc amalgam, potassium amalgam, sodium amalgam, ALUMINIUM amalgam, and tin amalgam.

The correct answer is (B) False

The best explanation: A metastable solution is one which is stable when undisturbed but is CAPABLE of REACTION if disturbed. Supersaturated solutions are stable when undisturbed and precipitates out CRYSTALS of the solute when disturbed. HENCE, supersaturated solutions are metastable.

Right choice is (C) 71.36 BAR

Easiest explanation: Given,

Solubility of natural gas, S = 0.8 mole of gas/kg of water = 0.8 molal

Hence, moles of natural gas in mixture, nNG = 0.8 mole

At NTP, pressure, PNG = 1.01325 bar

Number of moles of water in 1000 g, NW = mass/molar mass

nw = 1000g / (18g/mole) = 55.56 mole

Mole fraction of natural gas in the mixture, XNG = nNG/ (nNG + nw)

XNG = 0.8/(0.8 + 55.56) = 0.0142

Using Henry’s law PNG = KH x XNG

KH = PNG/XNG = 1.01325 bar/0.0142 = 71.36 bar.

Correct option is (a) 2.333 M

The explanation is: GIVEN,

V1 = 2 L

V2 = 4 L

V3 = 6L

M1 = 1 M

M2 = 2 M

M3 = 3 M

Resultant concentration, MR = (M1V1 + M2V2 + M3V3)/(V1 + V2 + V3)

MR = ( 2 x 1 + 4 x 2 + 6 x 3 )/( 2 + 4 + 6) = 2.333 M.

Correct choice is (c) H2O

To elaborate: The principle of SOLUBILITY states that ‘like dissolves like’. Following this, it is seen that 3-Aminopropan-1-ol is a highly POLAR compound since it bears an amine group as well as a HYDROXYL group. The polarity of amine group is due to the highly electronegative nature of N atom in N – H and C – N bonds. Since water is the most polar solvent AMONGST the four, it will dissolve the solute to GREATEST extent.

Correct option is (b) 0.5000 m

For explanation: Given,

Mass of NaCl, m = 58.5 g

MOLES of NaCl, n = mass/molar mass

n = 58.5g/(58.5 g/mole) = 1 mole

Molality = moles of solute/mass of solvent (in kg)

Volume of solvent = 2000 ml = 2 L

Mass of solvent = volume X density = 2 L x 1 kg/L = 2 kg

Molality = 1 mole/2 kg = 0.5 molal.

Right option is (c) 40

To explain I would say: Given,

CONCENTRATION, c = 0.3 MOLE/L

Volume, v = 100 ml = 0.1 L

Number of moles, n = concentration (mole/L) x volume (L)

n = 0.3 mole/L x 0.1 L = 0.03 moles

0.03 moles of XCL2 corresponds to 3.33g, then 1 mole CONTAINS 3.33/0.03 = 111 g of XCl2.

Hence, molecular mass = 111 g/mole.

Let x be the atomic mass. Then –

111 = x + 2(35.5)

x = 40g/mole.

Right answer is (a) 0.0196

To explain: GIVEN,

Mass of A, mA = 25g

Molar mass of A = 25 g/mole

Number of MOLES of A, nA = mA/MA = 25/25 = 1 mole

Number of moles of B, nB = 50 moles

Mole fraction of A, xA = nA/(nA+nB) = 1/(1 + 50) = 0.0196.

Right choice is (B) 671.67 °R

For explanation I would say: °R represents the temperature measured on Rankine scale. TYPICALLY, boiling point of water is measured as 100 °C on the Celsius scale. The conversion of Celsius to Rankine scale is R = C X 9/5 + 491.67.

Considering boiling point of water as 100 °C, R = 100 x 9/5 + 491.67 = 671.67 °R

°F, °r REPRESENT the Fahrenheit and REAUMUR scale, respectively.

The CORRECT answer is (B) Saturated

Explanation: Saturated solutions are those which contain maximum amount of solute that is SOLUBLE and cannot be further dissolved. Dilute solutions have a very low concentration of the SALT. Unsaturated solutions have concentration of solute lesser than its solubility. SUPERSATURATED solutions contain more amount of solute than how much is soluble in the solvent. In other words, adding more solute to a saturated solution results in a supersaturated solution.

Correct answer is (c) 10.307 mL

Explanation: Given,

FINAL concentration, N2 = 0.25 N

Final volume, V2 = 500 mL = 0.5 L

Consider 100 KG of solution.

100 kg of STOCK solution contains 37.2 kg acid.

Volume of stock solution containing 37.2 kg acid = 100kg/(1.19 kg/L) = 84.0336 L

Number of moles of HCl acid, n = MASS of acid/molar mass of acid

n = 37.2 kg/(1 + 35.5) = 1.01918 kmole = 1019.18 mole

Molarity, M = n/volume of stock solution = 1019.18/84.0336 = 12.1282 M

Normality of stock solution, N1 = nf x Molarity = 1 x 12.1282 = 12.1282 N

Using EQUIVALENCE equation N1 x V1 = N2 x V2:

Volume of stock solution to be added, V1 = (0.25 x 500 mL)/(12.1282) = 10.307 mL.

Right option is (a) S = (KSP/84375)^1/8

To explain: The dissociation reaction is represented as V3(PO4)5 → 3V^5+ + 5PO4^3-

If S is the SOLUBILITY of V^5+ and PO4^3- ions then KSP = [3V^5+]^3 [5PO4^3-]^5, where the SQUARE BRACKETS indicate the molar concentrations of the ions in the SOLUTION. KSP can then be written as KSP = [3S] ^3[5S] ^5 = 3^3 x 5^5 x S^8 gives KSP=84375 x S^8.

Therefore, on rearranging, S = (KSP/84375)^1/8.