CBSE Questions for Class 11 Medical Chemistry Some Basic Concepts Of Chemistry Quiz 13 - MCQExams.com

A sample of a gas at STP contains $$3.01 \times 10^{23}$$ molecules and has a mass of 22.0 grams.
This gas is most likely :
  • $$CO_2$$
  • $$O_2$$
  • $$N_2$$
  • CO
  • NO
$$0.16\ g$$ of an organic compound containing sulphur produces $$0.233\ g$$ of $$BaSO_{4}$$. Percentage of sulphur in the compound is :
  • $$20$$
  • $$80$$
  • $$50$$
  • $$10$$
Maximum percentage of chlorine is in :
  • Chloral
  • Pyrene
  • Ethylidene chloride
  • PVC
Statement I : At STP, 22.4 liters of He will have the same volume as one mole of $$\displaystyle { H }_{ 2 }$$ (assume ideal gases).
Statement II : One mole or 22.4 liters of any gas at STP will have the same mass.
  • true, false
  • false, true
  • true, true, correct explanation
  • true, true, not correct explanation
The system that contains the maximum number of atoms is :
  • $$4.25\ g$$ of $$N{H}_{3}$$
  • $$8\ g$$ of $${O}_{2}$$
  • $$2\ g$$ of $${H}_{2}$$
  • $$4\ g$$ of $$He$$
What is the percentage of calcium in calcium carbonate $$(CaCO_3)$$? 
  • 30%
  • 40%
  • 50%
  • 60%
What mass of $$AgI$$ will dissolve in $$1.0L$$ of $$1.0M$$ $${NH}_{3}$$? neglect change in conc. of $${NH}_{3}$$
(Given : $${K}_{sp}=1.5\times {10}^{-16};{K}_{f}[Ag{({NH}_{3})}_{2}^{+}]$$; (At.mass $$Ag=108,I=127$$)
  • $$4.9\times {10}^{-5}g$$
  • $$0.0056g$$
  • $$0.035g$$
  • $$0.011g$$
According to Avogadro's law the correct statement are
a) Volume of gas is directly proportional to the no. of moles at constant T and P.
b) The pressure of gas is directly proportional to temp. of the gas under all conditions.
c) Equal volumes of different gases under similar conditions consist of equal no. of molecules.
d) Equal volumes of different gas under same conditions have equal no. of atoms.
  • b,c
  • a,c
  • d,b
  • c,d
Natural abundances of $$^{12}C$$ and $$^{13}C$$ isotopes of carbon are $$99\%$$ and $$1\%$$, respectively. Assuming they only contribute to the mol. wt. of $$C_2F_4$$, the percentage of $$C_2F_4$$ having a molecular mass of $$101$$ is:
  • $$1.00$$
  • $$98$$
  • $$0.198$$
  • $$99$$
1 g of silver gets distributed between $$10\ cm^3$$ of molten zinc and $$100\ cm^3$$ of molten lead at $$800^o C$$. The percentage of silver in the zinc layer in approximately:
  • 89%
  • 91%
  • 97%
  • 94%
How do you determine the mass percent of a solute in a solution?
  • $$ \displaystyle \text {Mass percent } = \dfrac { \text { mass of solute} }{ \text { mass of solution }} \times 100$$ %
  • $$ \displaystyle \text {Mass percent } = \dfrac { \text { mass of solution} }{ \text { mass of solute }} \times 100$$ %
  • $$ \displaystyle \text {Mass percent } = \dfrac { \text { moles of solute} }{ \text { mass of solution }} \times 100$$ %
  • $$ \displaystyle \text {Mass percent } = \dfrac { \text { mass of solute} }{ \text { moles of solution }} \times 100$$ %
  • $$ \displaystyle \text {Mass percent } = \dfrac { \text { moles of solute} }{ \text { moles of solution }} \times 100$$ %
What is the percentage of sulphur in sulphuric acid $$(H_2SO_4)$$?
  • 32%
  • 32.45%
  • 32.65%
  • 32.55%
The density of a liquid is 1.2 g/mL. That are 35 drops in 2 mL. The number of molecules in 1 drop is (molecular weight of liquid = 70): 
  • $$\frac{1.2}{35} N_A$$
  • $$\left (\frac{1}{35} N_A \right )^2$$
  • $$\frac{1.2}{(35)^2} N_A$$
  • $$1.2 N_A$$
Avogadro's law shows the relationship between which two variables?
  • Volume and number of moles
  • Pressure and number of moles
  • Volume and pressure
  • Temperature and pressure
  • Temperature and number of moles
Percentage purity of a sample of gold is $$85\%$$. How many atoms of gold are present in its $$1$$ gram sample? (Atomic mass of gold $$=197$$u).
  • $$3.0\times 10^{21}$$
  • $$2.6\times 10^{23}$$
  • $$2.6\times 10^{21}$$
  • $$4.5\times 10^{26}$$
Calculate the mole percentage of $$CH_{3}OH$$ and $$H_{2}O$$ respectively in $$60$$% (by mass) aqueous solution of $$CH_{3}OH$$.
  • $$45.8, 54.2$$
  • $$54.2, 45.8$$
  • $$50, 50$$
  • $$60, 40$$
The vapour pressure of a solution of a non -volatile electrolyte (A) in a solvent (B) is $$95\%$$ of the vapour pressure of the solvent at the same temperature. If $$M_b=0.3 M_A$$, where $$M_B$$and $$M_A$$ are molecular weights of B and A respectively, the weight ratio of the solvent and solute are:
  • 0.15
  • 5.7
  • 0.2
  • 4.0
Two vessels of volumes $$16.4\ L$$ and $$5\ L$$ contains two ideal gases of molecular existence at the respective temperature of $$27^{\circ}C$$ and $$227^{\circ}C$$ and exert $$1.5$$ and $$4.1$$ atm, respectively. The ratio of the number of molecules of the former to that of the later is:
  • $$2$$
  • $$1$$
  • $$\dfrac {1}{2}$$
  • $$\dfrac {1}{3}$$
  • $$3$$
The mass of one twelfith of the mass of one carbon 12 atoms is 
  • $$1.68 \times 10^{-24}g$$
  • 1.008 g
  • -12 g
  • $$3.66 \times 10^{24}g$$
How many hydroxide ions are present in 2.5 mol of $$Ca(OH)_2 $$ ?
$$(N_A=6\times10^{23})$$
  • $$3\times10^{23}$$
  • $$6\times10^{23}$$
  • $$1.5\times10^{24}$$
  • $$3\times10^{24}$$
A 1.85 g sample of an arsenic-containing pesticide was chemically converted to $$AsO_4^{3-}$$ (atomic mass of As = 74.9) and titrated with $$Pb^{2+}$$ to form $$Pb_3(AsO_4)_2$$. If 20 mL of 0.1 M $$PB^{2+}$$ is required to reach the equivalence point, the mass percentages of arsenic in the pesticide sample is closest to
  • 8.1
  • 2.3
  • 5.4
  • 3.6
20 ml of $$H_2O_2$$ after acidification with dil $$H_2SO_4$$ required 30 ml of N/2 $$KMnO_4$$ for complete oxidation .Calculate the $$\%$$ of $$H_2O_2$$ in g/lit.
  • 10.75 g/lit
  • 11.75 g/lit
  • 12.75 g/lit
  • 13.75 g/lit
If  the molar concentration of $$Pbl_2$$ is then the $$1.5 \times 10^{-3}\,\, mol \, L^{-1}$$ concentration of iodide ions in g ion $$L^{-1}$$ is:
  • $$3.0 \times 10^{-3}$$
  • $$6.0 \times 10^{-3}$$
  • $$0.3 \times 10^{-3}$$
  • $$0.6 \times 10^{-3}$$
Volume of $$O_{2}$$ remained after the first combustion?
  • $$4\ ml$$
  • $$2\ ml$$
  • $$0$$
  • $$8\ ml$$
The percentage of $$Se$$ in peroxidase anhydrous enzyme is $$0.5$$% by weight (atomic weight $$= 78.4$$). Then minimum molecular weight of peroxidase anhydrous enzyme is:
  • $$1.568\times 10^{4}$$
  • $$1.568\times 10^{3}$$
  • $$15.68$$
  • $$3.136\times 10^{4}$$
The mass of a mixture containing HCl and $$H_2SO_4$$ is 0.1 g. On treatment with an excess of an $$AgNO_3$$ solution, reacted with this acid mixture gives 0.1435 g of AgCl. Mass % of the $$H_2SO_4$$ mixture is :
  • 30
  • 60
  • 59
  • None of these
During the preparation of $$H_{2}S_{2}O_{8}$$ (per disulphuric acid) $$O_{2}$$ gas also releases at anode as by product. When $$9.72\ L$$ of $$H_{2}$$ releases at cathode and $$2.35\ L\ O_{2}$$ at anode at STP, the weight of $$H_{2}S_{2}O_{8}$$ produced in gram is:
  • $$87.12$$
  • $$43.56$$
  • $$83.42$$
  • $$51.74$$
The amonia evolved from 2g of a compound in Kjeldahl's estimation of nitrogen neutralizes 10 mL of 2 M $${ H }_{ 2 }S{ O }_{ 4 }$$ solution. The weight percentage of nitrogen in the compound is
  • $$28$$
  • $$14$$
  • $$56$$
  • $$7$$
The common isotopes of carbon are $$^{ 12 }C$$ and $$^{ 13 }C$$. The average mass of carbon is $$12.01115$$ amu. What is the abundance of $$^{ 13 }C$$ isotope ?.
  • $$1.115\%$$
  • $$98.885\%$$
  • $$0.480\%$$
  • $$99.52\%$$
A gas mixture contains $$50\%$$ helium and $$50\%$$ methane by volume. What is the percentage by mass of methane in the mixture?
  • $$20\%$$
  • $$30\%$$
  • $$50\%$$
  • $$80\%$$
If $$224ml$$ of triatomic gas has a mass of $$1g$$ at $$273K$$ and $$1atm$$ pressure, then the mass of one atom is-
  • $$8.30\times {10}^{-23}gm$$
  • $$2.08\times {10}^{-23}gm$$
  • $$5.53\times {10}^{-23}gm$$
  • $$6.24\times {10}^{-23}gm$$
A 5 mL (specific gravity 1.02) of chlorine water is treated with an excess of KI.The liberate iodine required 26 mL of $$ 0.15 \,M-Na_2SO_4$$ solution.Calculate the percentage of $$Cl_2$$ (by weight) the chloride water.Chloride water is a solution of free chlorine in water
  • $$0.388 \%$$
  • $$0.301 \%$$
  • $$0.307 \%$$
  • $$3.02 \%$$
$$0.3\ g$$ of an oxalate salt was dissolved in $$100\ mL$$ solution. The solution required $$90\ mL$$ of $$N/20\ KMnO_4$$ for complete oxidation.The % of oxalate ion in salt is: 
  • $$33\%$$
  • $$66\%$$
  • $$70\%$$
  • $$40\%$$
5 g of a sample of bleaching powder is treated with excess acetic acid and KI solution. The liberated $$I_2$$ required 50 ml of N/10 hypo solution. The % available chlorine in sample is
  • 3.55
  • 7.0
  • 35.5
  • 28.2
A $$1.85\ g$$ sample of an arsenic-containing pesticide was chemically converted to $$AsO_{4}^{3-}$$ (atomic mass of $$As = 74.9)$$ and titrated with $$Pb^{2+}$$ to form $$Pb_{3}(AsO_{4})_{2}$$. If $$20\ mL$$ of $$0.1\ M\ Pb^{2+}$$ is required to reach the equivalence point, the mass percentage of arsenic in the pesticide sample is closest to:
  • $$8.1$$
  • $$2.3$$
  • $$5.4$$
  • $$3.6$$
Choose the correct answers from the alternatives given :
Age of fossil may be found out by determining the ratio of two isotopes of carbon. The isotopes are ____________________.
  • C-12 and C-13
  • C-13 and C-14
  • C-12 and C-14
  • C-12 and carbon black
Which one of the following is not required for the formation of photochemical smog?
  • Nitrogen oxide
  • Methane
  • Volatile organic compounds
  • Ozone
4.0 g of a mixture of $$NaCl$$ and an unknown metal iodide $$MI_{2}$$ was dissolved in a water to form its aqueous solution. To this aqueous solution, The aqueous solution $$AgNO_{3}$$ was added gradually so that silver halides are precipitated. The precipitates were weighed at regular interval and the given curve for the mass of precipitate versus volume of $$AgNO_{3}$$ added was obtained. With the knowledge of the fact that halides are precipitated successively i.e. when one halide is precipitating , the other halide remains in the solution, answer the following questions:
(Molar mass of $$Ag = 108,\ I = 127,\ Na = 23$$).
Points $$P$$ and $$Q$$ are: $$P(20, 4.8),\ Q(37, 7.25)$$
What is the approximate mass percentage of $$MI_{2}$$?
  • 25
  • 40
  • 60
  • 75
0.5g sample of a sulphite salt was dissolved in 20ml solution and 20ml of this solution required 10ml of 0.002M acidified permanganate solution. Hence, the $$\%$$ by mass of sulphite in the sulphite salt is:
  • $$2\%$$
  • $$4\%$$
  • $$6\%$$
  • $$8\%$$
$$2$$g of brass containing $$Cu$$ and $$Zn$$ only reacts with $$3$$M $$HNO_3$$ solution. Following are the reactions taking place.

$$Cu(s)+HNO_3(aq)\rightarrow Cu^{2+}(aq)+NO_2(g)+H_2O(l)$$

$$Zn(s)+H^+(aq)+{NO}^-_3(aq)\rightarrow NH^+_4(aq)+Zn^{2+}(aq)+H_2O(l)$$

The liberated $$NO_2(g)$$ was found to be $$1.04$$L at $$25^o$$C and $$1$$ atm $$[Cu =63.5, Zn=65.4]$$.
How many grams of $$NH_4NO_3$$ will be obtained in the reaction?
  • $$0.405$$g
  • $$0.0428$$g
  • $$0.2018$$g
  • $$0.358$$g
When a mixture of $$NaBr$$ and $$NaCl$$ is repeatedly digested with sulphuric acid, all the halogens are expelled and $$Na_{2}SO_{4}$$ is formed quantitatively. With a particular mixture, it was found that the weight of $$Na_{2}SO_{4}$$ obtained was precisely the same as the weight of $$NaBr - NaCl$$ mixture taken. Calculate the ratio of the weights of $$NaCl$$ and $$NaBr$$ in the mixture.
  • $$1:1.454 $$
  • $$2:1.31$$
  • $$1.454 : 1$$.
  • $$1.31:2$$
Calculate the mass percent (w/w) of sulphuric acid in a solution prepared by dissolving $$4$$ g of sulphur trioxide in a $$100$$ml sulphuric acid solution containing $$80$$ mass percent (w/w) of $$H_2SO_4$$ and having a density of $$1.96\ g/ml$$(molecular weight of $$H_2SO_4=98$$) Take reaction $$SO_3+H_2O\rightarrow H_2SO_4$$.
  • $$80.8\%$$
  • $$84\%$$
  • $$41.65\%$$
  • None of these
Mole fraction of ethyl alcohol in aqueous ethyl alcohol $$(C_2H_5OH)$$ solution is $$0.25$$. Hence percentage of ethyl alcohol by weight is:
  • $$54\%$$
  • $$25\%$$
  • $$75\%$$
  • $$46\%$$
32 g of a sample of $$FeSO_4$$.$$7H_2O$$ were dissolved in dilute sulphuric acid and water and its volume was made up to 1 litre. 25 mL of this solution required 20 mL of 0.02 M $$KMnO_4$$ solution for complete oxidation. Calculate the mass % of $$FeSO_4$$.$$7H_2O$$ in the sample.
  • 34.75
  • 69.5
  • 89.5
  • None of these
What is the mass percentage of carbon tetrachloride if $$22g$$ of benzene is dissolved in $$122g$$ of carbon tetrachloride?
  • $$84.72$$%
  • $$15.28$$%
  • $$50$$%
  • $$44$$%
What is the mass per cent of oxygen in ethanol?
  • $$52.14\%$$
  • $$13.13\%$$
  • $$16\%$$
  • $$34.73\%$$
0.2 g of an organic compound contains $$C,\ H,\ O$$ on combustion, it yields 0.15 g of $$CO_2$$ and 0.12 g $$H_2O$$. The percentage of $$C,\ H$$ and $$O$$ respectively is:
  • $$C=15$$ %, $$H= 20$$ %, $$O=65$$ %
  • $$C=10$$ %, $$H=8.2$$ %, $$O=81.8$$%
  • $$C=12.2$$ %. $$H=8.8$$ %, $$O=79$$ %
  • $$C=20$$ %, $$H=6.66$$ %, $$O=73.34$$ %
Flask I contains a gaseous mixture of $$He(g)$$, $$H_2(g)$$, in the molar ratio of $$1:\sqrt{2}$$. The gas mixture is allowed to effuse through a fine orifice in the flask l and is collected in flask ll. What is the average molar mass of gas mixture initially collected in flask ll?
  • 3.20
  • 2.33
  • 4.00
  • None of these
32g of a sample of $${ FeSO }_{ 4 }.{ 7H }_{ 2 }O$$ where the dissolved in dilute Sulphuric acid and water and it's volume was made up to 1 litre, 25 mL of this solution required 20 mL of 0.02 $$M\ KMn{ O }_{ 4 }$$ solution of complete oxidation. Calculate the weight % of $$FeS{ O }_{ 4 }.{ 7H }_{ 2 }O$$ in the sample. 
  • 34.75
  • 69.5
  • 89.5
  • None of these
Natural water contains about $$0.02\%$$ $$D_2O$$ (heavy water). When it is enriched to $$20\%$$ (by volume), calculate the fraction of weight due to neutrons in 1 mole of sample.
  • $$0.355$$
  • $$0.444$$
  • $$0.455$$
  • $$0.500$$
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