MCQ Questions for Class 11 Medical Chemistry Some Basic Concepts Of Chemistry Quiz 4

Temporary hardness is due to bicarbonates of

$Mg^{2+}\, and\, Ca^{2+}$ , it is removed by addition of CaO as follows:

$Ca(HCO_3)_2\,+\, CaO\, \rightarrow\, 2CaCO_3\,+\, H_2O$
Mass of

$CaO$ required to precipitate 2 g

$CaCO_3$ is:

0%
$2 g$
0%
$0.56 g$
0%
$0.28 g$
0%
$1.12 g$

Explanation

$Ca(HCO_3)_2 + CaO \rightarrow 2CaCO_3+H_2O$

Molecular mass of

$CaO=40+16=56 \ g$

Molecular mass of

$CaO_3=40+12(16 \times 3)=100 \ g$

Accoridng to the equation,

$2$ moles of

$CaCO_3$ i.e

$200 \ g$ of

$CaCO_3$ are formed from

$56 \ g \ CaO$

$2 \ g$ of

$CaCO_3$ will be formed from

$=\cfrac {2 \times 56}{200}=0.56 \ grams$

$3.01\times 10^{23}$ molecules of elemental Sulphur will react with 0.5 mole of oxygen gas completely to produce

0%
$6.02\times 10^{23}$ molecules of $SO_3$
0%
$6.02\times 10^{23}$ molecules of $SO_2$
0%
$3.01\times 10^{23}$ molecules of $SO_3$
0%
$3.01\times 10^{23}$ molecules of $SO_2$

Explanation

$\underset {\underset {\frac {1}{2}mole}{1 mole}}{S}+\underset {\underset {\frac {1}{2}mole}{1 mole}}{O_2}\rightarrow \underset {\underset {\frac {1}{2}mole}{1 mole}}{SO_2}$

$3.01\times 10^{23} {\;} 0.5 mole {\;} ?$

$\therefore 3.01\times 10^{23}$ molecules of

$SO_2$ will be formed.

The relative atomic mass of naturally occurring chlorine is not a whole number. What is the reason for this ?

0%
Chlorine atoms can have different number of neutrons
0%
Naturally occurring chlorine cannot be obtained pure
0%
Chlorine is unstable
0%
The mass of the electrons has been included

Explanation

The relative atomic mass of an element is the average of the atomic masses of all the chemical element's isotopes as found in a particular environment, weighted by isotopic abundance.

Chlorine has two isotopes available in Nature.

One has At.mass = 35 which forms roughly

$75\%$ of the naturally available Chlorine.

Another has At.mass = 37 which forms roughly

$25\%$ of the naturally available Chlorine.

So they have fractional atomic mass.

Hence, the correct option is

$\text{A}$

A compound was found to contain 5.37% nitrogen. What is the minimum molecular weight of compound ?

0%
$26.07$
0%
$2.607$
0%
$260.7$
0%
None of these

Explanation

$5.37 g$ of

$N$ in

$100 g$ compound.

$14 g N$ =

$\displaystyle\frac{100\times14}{5.37} = 260.7$ g compound

which is the minimum molecular wt as it should have at least one

$N.$

Hence (c) is the correct answer.

Three containers A, B and C of equal volume, contain

$N_2$ ,

$NO_2$ and

$CO_2$ respectively, at the same temperature and pressure. The ascending order of their masses is:

0%
A, C, B
0%
C, A, B
0%
B, C, A
0%
C, B, A

Explanation

Since the ideal gas equation is same for all the gases, there will be same number of moles of each gas. Hence, the ascending order of their masses is the ascending order of their molecular weight.

Molecular weight of

${ N }_{ 2 }=$ 28

Molecular weight of

${ NO }_{ 2 }=$ 46

Molecular weight of

${ CO }_{ 2 }=$ 44

Hence, the correct order would be A, C, B .

Aluminium reduces manganese dioxide to manganese at high temperature. The amount of aluminium required to reduce one gram mole of manganese dioxide is

0%
1/2 gram mole
0%
1 gram mole
0%
3/4 gram mole
0%
4/3 gram mole

Explanation

$4AI + 3MnO_2 \rightarrow 3Mn + 2Al_2 O_3$
To reduce 3 moles of

$MnO_2$ required moles of AI = 4
So, for one mole of

$MnO_2$ required moles of AI will be = 4/3

The volume of

$0.5 M$ aqueous

$NaOH$ solution required to neutralize

$10 ml$ of

$2 M$ aqueous

$HCl$ solution is

0%
$20 \ ml$
0%
$40 \ ml$
0%
$80 \ ml$
0%
$120 \ ml$

Explanation

$NaOH {\;} : HCl$

$N_1V_1=N_2V_2$

$0.5\times V=2\times 10$

$V=40 mL$

Number of moles of 1

$m^3$ gas, at STP, are:

0%
44.6
0%
40.6
0%
42.6
0%
48.6

Explanation

At STP , volume of 1 mol

$=$ 22.7 L

$m^3$ has 1000 L
Then, n (no. of moles) in 1

$m^3$

$= \displaystyle\frac{1000}{22.7}$

$= 44.642 \ mol$ .

Which law stated that 'matter is neither created nor destroyed'?

0%
Law of multiple proportion
0%
Law of conservation of energy
0%
Law of constant composition
0%
Law of conservation of mass

A compound was found to contain 5.37% nitrogen. What is the minimum molecular weight of compound?

0%
26.07
0%
2.607
0%
260.7
0%
None of these

Explanation

5.37 9 N is present in 100 9 compound
14gN =

$\frac {100 \times 14}{5.37}=260.7$ g compound (i.e., minimum molecular weight as it should have atleast one N).

A chemical equation is balanced in accordance with the law of

0%
conservation of mass
0%
multiple proportion
0%
constant proportion
0%
reciprocal proportion

Explanation

There must be the same number of each element on both side of the chemical equation. It adheres with the conservation of mass.

Option

$A$ is correct.

Natural Boron is a mixture of

$_{\text{5}}{{\text{B}}^{{\text{10}}}}\;{\text{and}}{\;_{\text{5}}}{{\text{B}}^{{\text{11}}}}$ with relative abundance of 20% and 80 %. Find atomic weight of boron.

0%
10
0%
11
0%
10.8
0%
11.2

The law of conservation of mass was given by :

0%
Dalton
0%
Proust
0%
Lavoisier
0%
Berzelius

A sample of

$CaCO_3$ has Ca =40%, C = 12% and O = 48% by mass. If the law of constant proportion is true then the weight of Ca in 16g of

$CaCO_3$ made from different processes will be -

0%
64 g
0%
0.64g
0%
6.4g
0%
4.6 g

Explanation

Molecular weight of

$CaCO_3$ = 100g

Percentage of Ca = 40 %

Let, law of constant proportion is true.

So, mass of Ca in 100 g of

$CaCO_3$ =

$\dfrac{40}{100} \times 100 = 40g$

So, weight of Ca in 16g of

$CaCO_3$ =

$\dfrac{40}{100} \times 16g = 6.4g$

Which atom contains exactly 15 neutrons?

0%
$P^{32}$ (atomic number $= 17$ )
0%
$S^{32}$ (atomic number $= 16$ )
0%
$O^{15}$ (atomic number $= 8$ )
0%
$N^{15}$ (atomic number $= 7$ )

Explanation

$mass\space number= no. of \space protons + no. of\space neutrons$
Given that mass number of P = 32

Atomic number (no. of electrons

$=$ no. of protons)

$=$ 17

Number of neutrons

$= 32 - 17 = 15$

Hence, P satisfies the requirement.

A sugar solution contains

$15\%$ sugar by weight. When the solution is heated,

$40\%$ sugar is left in the solution. The amount of water which is disappeared is:

0%
$0.0625\;g$
0%
$62.5\;g$
0%
$0.625\;g$
0%
$6.25\;g$

Explanation

Let the mass of solution

$=100\;g$
Mass of sugar

$=15\;g$
Mass of water

$=100-15=85\;g$
On heating some amount water is disappeared and let the new amount of solution is

$(X)\;g$ , which contain

$40\%$ sugar equal to

$15\;g$

$X\times\displaystyle\frac{40}{100}=15$

$x=37.5\;g$
After heating mass of solution is

$=37.5\;g$
Mass of water = Mass of solution - Mass of water

$=37.5-15=22.5$
Amount of water disappeared on heating

$=(85-22.5)=62.5\;g$

A sample of

$CaCO_3$ has

$Ca=40\%,\,C=12\%$ and

$O=48\%$ . If the law of constant proportion is true then the weight of

$Ca$ in

$16\;g$ of

$CaCO_3$ made from different processes will be

0%
$64\;g$
0%
$0.64\;g$
0%
$6.4\;g$
0%
$4.6\;g$

Explanation

Gram Molecular Mass of

$CaCO_3$

$=40+12+16\times3=40+12+48=100\;gm$

$100\;gm\;CaCO_3$ contain

$=40\;g\;Ca$

$\therefore\;16\;g\;CaCO_3$ will contain

$=\displaystyle\frac{40}{100}\times16=6.4\;g\;Ca$

In a chemical reaction, when 14 g of sodium carbonate reacted with 10g of acetic acid (ethanoic acid), then it was observed that, 16.67 g of sodium acetate solution in water and 7.33 g of carbon dioxide were produced. Which law does this depicts?

0%
Law of definite proportions
0%
Law of conservation of mass
0%
Law of constant proportions
0%
Avogadro's law

Explanation

In the given reaction,

$\underset {(14g)}{\text {Sodium carbonate}}+\underset {(10g)}{\text {Ethanoic acid}}\Rightarrow \underset {(16.67)}{(Sodium ethanoate+water)}+\underset {(7.33 g)}{Carbon dioxide gas}$
Total mass of all reactants combined

$=14 g+10 g=24 g$
Total mass of all the products formed

$= 16.67 g + 7.33 g =24 g$ .
It is observed that Total mass of all reactants combined

$= 24 g =$ Total mass of all the products formed. Therefore, the given observations are in agreement with the law of conservation of mass.

Among the following quantities:
(i) mass number
(ii) average mass of a Carbon atom in amu
(iii) the charge of nucleus in amu and
(iv) mass of a Carbon -12 atom in grams

0%
only (i) is whole number
0%
only (i) and (iii) are whole number
0%
only (i) and (iv) are whole numbers
0%
only (iii) and (iv) are whole numbers

Explanation

(1) The mass number is always the whole number because the mass number is the total number of neutrons and protons in the nucleus of the atom and an atom never contains fractional or an integer number of protons or neutrons.

(2) Average mass of carbon atom in

$amu$ is

$12.011u$ . It is in decimal and can be written as fractional form.

(3) Charge on the nucleus in

$amu$ :- Charge on the nucleus is equal to the number of protons and the number of protons are always whole.

(4) Mass of carbon atom=

$\cfrac {Mass\quad of\quad carbon}{Avogadro\quad number}$

$=\cfrac {12g}{6.022\times 10^{23}}$

$=1.99\times 10^{-23}$ grams

It is not a whole number.

How much MgO is obtained on heating 5 gm of

$\displaystyle \left ( MgCO_{3} \right )$ Magnesium carbonate?

0%
2.4 gm
0%
2.38 gm
0%
2.8 gm
0%
3.28 gm

Explanation

$\displaystyle MgCO_{3}\rightarrow MgO+CO_{2}$
Molecular weight of

$\displaystyle MgCO_{3}$
= 24 + 12 +16 x 3 = 84
Molecular weight of MgO
= 24 + 16 = 40
On heating 84 gms of

$\displaystyle MgCO_{3}$ the quantity of MgO obtained
= 40 gms

$\displaystyle \therefore$ On heating 5 gms of

$\displaystyle MgCO_{3}$ the quantity of MgO obtained

$\displaystyle = \frac{40}{84} X 5gms$
= 2.38 gms

The National Physical Laboratory is situated at:

0%
Kolkata
0%
New Delhi
0%
Bombay
0%
None of these

Explanation

The CSIR-National Physical Laboratory of India is situated in New Delhi.

It maintains standards of SI units in India and calibrates the national standards of weights and measures.

Hence, option

$B$ is correct.

The number of molecules in 1 L of oxygen and 1 L of nitrogen at STP will be:

0%
equal
0%
greater for $N_2$
0%
greater for $O_2$
0%
equal to Avogadro's number

When an inflated tyre bursts, the air escaping out will:

0%
get heated up
0%
be cooled
0%
not undergo any change in its temperature
0%
be liquified

Explanation

$\text{> Temperature falls when tyre bursts. This is due to adiabatic expension of air.}$

$\text{> The pressure of the air inside tyre is sufficiently greater than atmospheric pressure.}$

$\text{> When tyre brusts air comes out and work against surrounding.}$

$\text{> Due to this internal energy of bursts air decreases and temperature falls to be cooled.}$

Which pair has same percentage of carbon?

0%
$CH_3COOH \: and \: C_6H_{12}O_6$
0%
$CH_3COOH \: and \: C_{12}H_{22}O_{11}$
0%
$CH_3COOH \: and \: C_2H_5OH$
0%
$C_6H_{12}O_6 \: and \: C_{12}H_{22}O_{11}$

Explanation

The table below shows the ratio of different atoms present in a molecule.

$Compound$	$C$	$H$	$O$
$CH_3COOH$	1	2	1
$C_6H_{12}O_6$	1	2	1
$C_{12}H_5OH$	2	6	1
$C_{12}H_{22}O_{11}$	12;	22;	11

So,

$CH_3COOH$ and

$C_6H_{12}O_6$ have same % of

$C$ .

The law which suggests

$n_1 = n_2$ for two solutions at same temperature and pressure is

0%
van't Haff - avogadro's law
0%
van't Hoff Boyle's law
0%
van't Hoff's law
0%
Henry's law

$5.6$ litres of a monoatomic gas at S.T.P contain :

0%
$6.02\times {10}^{23}$ atoms
0%
$\frac14\times 6.02\times {10}^{23}$ atoms
0%
$\frac12\times 6.02\times {10}^{23}$ atoms
0%
$\frac13\times 6.02\times {10}^{23}$ molecules

Explanation

Sicne,

$22.4$ litres of a gas at S.T.P contains

$6.02\times {10}^{23}$ atoms.

$\therefore$

$5.6$ litres of a gas at S.T.P will contain

$\cfrac{5.6}{22.4}\times 6.02\times {10}^{23}=\cfrac{1}{4}\times 6.02\times {10}^{23}$ atoms.

The first organic substance ever prepared in the laboratory from the inorganic compound is:

0%
urea
0%
ethyl alcohol
0%
methane
0%
ethane

One atomic mass unit is equivalent to

0%
$1.67\times 10^{-27} g$
0%
$1.66\times 10^{-27} kg$
0%
$1.67\times 10^{-27} mg$
0%
$1.6\times 10^{-24} g$

Explanation

One amu

$=\frac {1}{N_A}=\frac {1}{6.02\times 10^{23}}$

$=1.66\times 10^{-24}g=1.66\times 10^{-27}kg$

So, the correct options are

$B$ and

$D$

In chulhas, gaps are left between the logs:

0%
to decrease the ignition temperature of the fuel
0%
to allow the air to enter and facilitate fuel burning
0%
to cut off the supply of air
0%
all of these

What is the percentage by weight of sulphuric acid if 13 g of H

$_2$ SO

$_4$ is dissolved to make 78 g of solution?

0%
13.2%
0%
14.28%
0%
20%
0%
16.6%

Explanation

Weight of sulphuric acid = 13g
Weight of solution = 78g
Therefore w/W% =

$\frac{13}{78}\times 100$ = 16.6%

Calculate the (w/W)% of 10 g of potassium hydroxide in 40 g of solvent.

0%
25%
0%
20%
0%
30%
0%
40%

Explanation

Weight of KOH = 10g

Weight of solvent = 40g

Total weight of solution = 40 +10 =50g

Therefore,

$(\dfrac{w}{W})$ % =

$\dfrac{10}{50}\times 100$ =

$20$ %

What is the percentage by weight of sulphuric acid if 13 g of

$H_2SO_4$ is dissolved to make 78 g of solution?

0%
23.4
0%
20
0%
16.6
0%
13.2

Explanation

Weight of

$H_{2}SO_{4}$ = 13 g
Weight of solution = 78 g
Therefore (w/W)% =

$\dfrac{13}{78}\times 100$

$= 16.6$ %

The w/W % of 25 g of calcuim hydroxide in 50 g of solvent is_____ %

0%
40
0%
33.33
0%
36.3
0%
30

Explanation

Weight of

$Ca(OH)_{2}$ = 25g

Weight of solution = 75g

Therefore w/W% =

$\dfrac{25}{75}\times 100$ = 33.33%

Hence, the correct option is

$B$

Mass can neither be created nor destroyed. This is in agreement with which law of chemical combination?

0%
Law of definite proportion
0%
Law of multiple proportion
0%
Law of conservation of mass
0%
Law of conservation of momentum

What is the mass of the solvent present in 200 g of 25% (w/W) calcium hydroxide solution?

0%
150 g
0%
125 g
0%
175 g
0%
100 g

Explanation

Given that Mass of solution = 200g and let mass of solute = x
Now, mass of the solute can be calculated as follow:

$25 = \frac{x}{200}\times 100$
Thus, x = mass of solute = 50g
Therefore mass of solvent = mass of solution - mass of solute = 200-50 = 150g

1.008 grams of hydrogen combines with 35.453 g of chlorine to form 36.463 g of a pure compound (hydrogen chloride). Dalton's explanation for this experimental fact might be:

0%
One atom of hydrogen combines with 35.453 atoms of chlorine in this reaction
0%
Hydrogen and chlorine atoms always combine in a 1:35 ratio.
0%
Chlorine accepts hydrogen's electron to form polar covalent hydrogen chloride
0%
Hydrogen and chlorine atoms aren't created or destroyed in the process so the reactant mass is the same as the product mass.

The formula for % composition of a compound is:

0%
molar mass of a compound/mass due to specific component $\times$ 100
0%
mass due to specific component $\times$ 100
0%
mass due to specific component/molar mass of a compound $\times$ 100
0%
molar mass of a specific component/temperature $\times$ 100

Explanation

To calculate the per cent composition of a component in a compound: Find the molar mass of the compound by adding up the masses of each atom in the compound using the periodic table or a molecular mass calculator. Calculate the mass due to the component in the compound you are for which you are solving by adding up the mass of these atoms. Divide the mass due to the component by the total molar mass of the compound and multiply by 100.

$\text{composition of a compound}=\cfrac{\text{ Mass due to specific component}}{\text{molar mass of a compound}}\times 100$

Hence, the correct option is

$\text{C}$

What is the atomic mass (u) of chlorine?

0%
34
0%
35.5
0%
33
0%
35

A solution contains 100 g of urea in 400 g of water. Calculate the concentration in terms of mass by mass percentage of the solution.

0%
20
0%
25
0%
10
0%
80

Explanation

Mass of solute = 100 g

Mass of solvent = 400 g

Mass of solution = 400 + 100 = 500 g

Mass % of solution

$= \dfrac{\text{Mass of solute} \times 100}{\text{Mass of solution}}$

$= \dfrac{100 \times 100}{500}$

$= 20$ %

Hence, the correct option is

$\text{A}$

Which is not one of the laws of chemical combinations?

0%
Law of multiple proportion
0%
Law of conservation of mass
0%
Law of conservation of energy
0%
Law of definite proportion

Which of these would support the idea that mass is conserved in a reaction that produces gas as a product?

0%
Heating the reactants to ensure the reaction occurs in a gaseous state.
0%
Subtracting the mass of the gas from the mass of the solid and liquid products.
0%
Mixing the reactants and measuring their total mass.
0%
Trapping the gas and measuring its mass.

Mass number is denoted by:

0%
D
0%
S
0%
A
0%
Z

$AgNO_3+NaCl\rightarrow AgCl+NaNO_3$ . In this reaction, mass of

$AgNO_3$ and

$NaCl$ is equal to the mass of

$AgCl$ and

$NaNO_3$ . Then this chemical reaction satisfies:

0%
Law of constant composition
0%
Law of conservation of mass
0%
Gay Lussac's law
0%
Law of multiple proportion

During any chemical change, the total mass of the products is equal to the total mass of reactants. This is a statement according to:

0%
Law of conservation of mass
0%
Law of constant composition
0%
Law of multiple proportion
0%
Law of reciprocal proportion

In a chemical reaction,

$100 g$ baking soda mixture containing sodium bicarbonate and vinegar on heating gives

$43 g$ of carbon dioxide gas. What mass of solid residue is left in food?

0%
$54\ g$
0%
$55\ g$
0%
$56\ g$
0%
$57\ g$

Explanation

According to law of conservation of mass, total mass of reactants is equal to total mass of products. Here baking soda mixture on heating gives solid residue and carbon dioxide.

$M_{\text {Baking soda mixture}} = M_{\text {solid residue}} + M_{CO_{2}}$

or it can be written as:

$M_{\text {solid residue}} = M_{\text {Baking soda mixture}} - M_{CO_{2}}$

$(Eq 1)$

According to the question

$M_{\text {Baking soda mixture}} = 100 g$

$M_{CO_{2}} = 43 g$

Substituting the value in equation

$1$ , we get

The mass of solid residue is

$100g - 43g =57 g$

Who laid the foundation of chemical sciences by experimentally establishing laws of chemical combination along with other scientists?

0%
Proust
0%
Antoine Lavoisier
0%
Dalton
0%
None of the above

A solution is prepared by dissolving 60 g of sodium chloride in 400 g of water. What is the mass-by-mass percent of sodium chloride in this solution?

0%
18%
0%
13%
0%
0.13%
0%
0.15%

Explanation

Mass of NaCl dissolved

$=$ 60 g
Mass of water taken

$=$ 400 g
Total Mass of solution

$= 400 + 60 = 460\ g$

Mass / Mass % of NaCl in solution

$= \dfrac{\text{Mass of NaCl} \times 100}{\text{Mass of solution}}$

$= \dfrac{60 \times 100}{460} = 13.04$ %

Which scientist proposed the concept of atomic mass?

0%
Avogadro
0%
Gay Lussac
0%
Proust
0%
Dalton

Which law was given by Antoine L. Lavoisier?

0%
Laws of multiple proportion
0%
Law of conservation of mass
0%
Both A and B
0%
None of the above

Explanation

Antoine-Laurent Lavoisier established the law of conservation of mass.

It states that "mass can neither be created nor be destroyed in a chemical reaction."

So, the correct option is

$B$ .

If the % composition of a 'x' component is 35%, find the mass of the dried 'x' component in 100g? mixture + beaker = 50 g, mass of beaker = 23 g

0%
15.5 g
0%
9.45 g
0%
35.5 g
0%
13.4 g

Explanation

mass of beaker

$= 23g$
mass of mix + beaker

$= 50g$
mass of mixture

$= 50 - 23 = 27g$

$\%$ composition of mixture

$= 35\%$
Mass of the x component

$= 35 \times \dfrac{27}{100} = 9.45g$

CBSE Questions for Class 11 Medical Chemistry Some Basic Concepts Of Chemistry Quiz 4 - MCQExams.com

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Practice Class 11 Medical Chemistry Quiz Questions and Answers

CBSE Questions for Class 11 Medical Chemistry Some Basic Concepts Of Chemistry Quiz 4 - MCQExams.com

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Practice Class 11 Medical Chemistry Quiz Questions and Answers

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