MCQ Questions for Class 9 Chemistry Atoms And Molecules Quiz 9

Which of the following term is denoted as Formula Mass Unit?

0%
Compounds
0%
Molecules
0%
Molecules contains ions as constituents
0%
None

Which of the following statements are not summarized within Dalton's Atomic Theory?

0%
Atoms cannot be created or destroyed.
0%
Atoms are made of protons, neutrons and electrons.
0%
Atoms rearrange in chemical reactions.
0%
When atoms combine to form compounds, they combine in whole number ratios.

Explanation

Dalton's atomic theory was given by John Dalton.

According to his theory:

(a) Matter is made up of invisible particles known as atoms.

(b) The properties of all the atoms of a given element are the same including mass.

(d) Atoms are neither created nor destroyed.

(e) The formation of new products results from the rearrangement of existing atoms.

(f) Atoms of an element are identical in mass, size and properties.

So option

$B$ is correct.

What is the molar mass of ammonium carbonate

${({NH}_{4})}_{2}{CO}_{3}$ ?

0%
$48\ g/mol$
0%
$96\ g/mol$
0%
$82\ g/mol$
0%
$78\ g/mol$
0%
$192\ g/mol$

Explanation

$(NH_4)_2CO_3$ is the chemical formula of ammonium carbonate.

$N = 14 \times (2) = 28$

$H = 1 \times (4 \times 2) = 8$

$C = 12 \times 1 = 12$

$O = 16 \times 3 = 48$

Molar mass

$= 28 + 8 + 12 + 48 = 96\ g/mol$

Zinc sulphate contains 22.65% Zn and 43.9%

$H_2O$ . If the law of constant proportions is true, then the mass of zinc required to give 40 g crystals will be:

0%
90.6 g
0%
9.06 g
0%
0.906 g
0%
906 g

Explanation

$ZnSO_4-22.65\% Zn$

$43.9\% H_2O$

$100g$ crystal has

$22.65$

$Zn$

$40g$ crystal has

$x$

$Zn$

$x=\cfrac{40\times 22.65}{100}=\cfrac{906}{100}=9.06g$

Hence, mass of

$Zinc$ required is

$9.06g$ .

Select the smallest atom.

0%
$F$
0%
$Cl$
0%
$Br$
0%
$I$

Explanation

In a group, on moving down the group, the atomic radius increases as electrons are added to the new shell.

Hence, the smallest atom is

$\displaystyle F$ .

How many grams are there in a

$7.0$ mole sample of sodium hydroxide?

0%
$40.0g$
0%
$140.0\ g$
0%
$280.0\ g$
0%
$340.0\ g$
0%
$420.0\ g$

Explanation

The formula of sodium hydroxide is

$NaOH$

Atomic weight of

$Na$ =

$23\ {g}/{mol}$

Atomic weight of

$O$ =

$16\ {g}/{mol}$

Atomic weight of

$H$ =

$1\ {g}/{mol}$

$\therefore$ molecular weight of

$NaOH$ = atomic mass of

$Na$ + atomic mass of

$O$ + atomic mass of

$H$

$23 + 16 + 1 = 40\ {g}/{mol}$

Therefore, 1 mole of

$NaOH = 40\ g/mol$

7 moles of

$NaOH = 7 \ mole \times 40\ g/mol= 280g$

Hence, option

$B$ is correct.

The image below represents the formation of potassium bromide,

$KBr$ . Which law is represented by this reaction?

0%
Law of Conservation of Mass
0%
Law of Multiple Proportions
0%
Law of Definite Proportions
0%
Law of Stoichiometry

The reaction between dinitrogen monoxide,

$N_{2}O$ and oxygen gas,

$O_{2}$ , carried out at high pressures, results in the formation of dinitrogen tetroxide,

$N_{2}O_{4}$ , as the only product. The unbalanced equation for the reaction is:

$N_{2}O(g) +O_{2}(g)\rightarrow N_{2}O_{4}(g)$

Given the legend and the

$N_{2}O/O_{2}$ mixture shown below.
Which of the following represents the composition of the system after the reaction has gone to completion?

Explanation

Balanced reaction:

$N_{2}O(g) +1.5O_{2}(g)\rightarrow N_{2}O_{4}(g)$

1 molecule of

$N_2O$ reacts with 1.5 molecules of oxygen as per the balanced reaction.

6 molecules of

$N_2O$ reacts with 9 molecules of oxygen as per the balanced reaction.

Since the reactant is present in stoichiometric ratio so all the reactants will be converted to product i.e. 6

$N_2O_4$ molecules.

A student carries out the following reaction in the laboratory:

Sodium carbonate + Copper sulphate

$\rightarrow$ Copper carbonate + Sodium sulphate

How could you determine the reaction obeyed the law of conservation of mass?

0%
Mass of the sample after the reaction is compared to the mass before the reaction begins
0%
Mass of the sample as the reaction is run is measured
0%
Filtering the reactants
0%
Running the reaction in an open system

Explanation

Law of conservation of mass states that mass of the reactants before the reaction should be same as the mass of the products after the reaction.

We will measure the mass of the product and see if it is the same as the mass of the reactants. Both will be same, thus showing the law of conservation of mass is obeyed.

$\Rightarrow$ Mass of the reactants = Mass of the products after the reaction

What is the formula unit mass of sodium chloride?

0%
58.5
0%
35.5
0%
23
0%
40

Explanation

The formula of sodium chloride is

$NaCl$

Atomic weight of sodium

$(Na)$ is

$23\ g/mol$

Atomic weight of chloride

$(Cl)$ is

$35.45\ g/mol$

Therefore, the formula unit mass of sodium chloride

$(NaCl)$ is

$23+35.45 = 58.45\ g/mol$ which nearly equals to

$58.5\ g/mol$

Hence, option

$A$ is correct.

Identify the anion from

$KClO_3$ .

0%
$Cl^-$
0%
$O^{2-}$
0%
$ClO_3{^-}$
0%
None of the above

Explanation

The cation is

$\displaystyle K^+$ ion and the anion is

$\displaystyle ClO_3{^-}$ ion.

$\displaystyle KClO_3 \rightarrow K^+ +ClO_3{^-}$

What is the formula mass unit of

$HCl$ ?

0%
$36.5$
0%
$35.5$
0%
$32.5$
0%
$34.5$

Explanation

Formula mass unit of

$HCl$ is : Mass of hydrogen

$(1) +$ mass of chlorine

$(35.5) = (35.5+1) = 36.5$

Hence, option A is correct.

Which of the following correctly represents Dalton's symbols?

0%
1 : Oxygen, 2 : Hydrogen, 3: Nitrogen, 4: Carbon and 5: Sulphur
0%
1 : Hydrogen, 2 : Nitrogen, 3: Oxygen, 4: Carbon and 5: Sulphur
0%
1 : Hydrogen, 2 : Nitrogen, 3: Oxygen, 4: Sulphur and 5: Carbon
0%
1 : Hydrogen, 2 : Carbon, 3: Oxygen, 4: Sulphur and 5: Nitrogen

Explanation

The following correctly represents Dalton's symbols.
1: oxygen, 2: hydrogen, 3: nitrogen, 4: carbon, and 5: sulphur

Hence, option

$A$ is correct.

Which of the following would weight the least?

0%
$2$ gram atoms of nitrogen
0%
$1$ mole of silver
0%
$22.4$ liters of oxygen gas at $1$ atmospheric pressure and $273$ K.
0%
$6.02 \times 10^{23}$ atoms of carbon.

Explanation

A] 2g atoms of nitrogen means

$2\times 14 =$ 28g

B] 1 mole of silver = 107.8g.

C] 22.4 litres of oxygen = 32g.

$6.02\times 10^{23}$ atoms = 1 mole = 12 g of carbon.

So, option

$D$ has the least weight.

State whether the given statement is true or false:

An atom is electrically neutral.

0%
True
0%
False

An ion is produced as a result of gain or loss of electrons by an atom. In

$Au^{3+}$ ion, 3 electrons are ___________by

$Au$ atom.

0%
gained
0%
lost
0%
shared
0%
None of the above

Explanation

$Au$ looses 3 electrons to form the cation

$Au^{3+}$ .

When the size of a spherical nanoparticle decreases from

$\text {30 nm}$ to

$\text {10 nm}$ . The ratio surface area/volume becomes:

0%
$1/3$ of the original
0%
$3$ times the original
0%
$1/9$ of the original
0%
$9$ times the original

Explanation

From the given information.

$\dfrac{\left(surface\ area\right)}{volume}=\dfrac{\left(\pi d^{2}\right)}{\left(\dfrac{\pi d^{2}}{6}\right)}=\dfrac{6}{d}$

$d_{1}=\ 30nm\ ,\ d_{2}=10nm$

$\therefore$

$\dfrac{\left(\dfrac{surface\ area}{volume}\right)_{2}}{\left(\dfrac{surface\ area}{volume}\right)_{1}}=\dfrac{\left(\dfrac{6}{d_{2}}\right)}{\left(\dfrac{6}{d_{1}}\right)}\ =\ \dfrac{d_{1}}{d_{2}}$ =

$\dfrac{30}{10}$ =

$3$

Hence, the correct answer is option

$B$ .

The law of constant proportions was enunciated by:

0%
Dalton
0%
Berthelot
0%
Avogadro
0%
Proust

Explanation

Proust defined the law of constant proportions. It is also called as

$\text{Proust's law}$ . it states that "In a chemical substance the elements are always present in a definite proportion by mass".
Hence, the answer is option

$D$ .

How many moles of bromine water will be required to complete bromination of 6 moles of phenol?

0%
$6$
0%
$18$
0%
$12$
0%
$3$

Which one of the following atoms will have largest size?

0%
Ca
0%
Na
0%
Mg
0%
Be

Explanation

Atomic size increased down the group and decreases in the period from left to right. If we look at the position of

$Be, Mg$ , and

$Ca$ then it is observed that they are present in the same column which indicates

$Ca$ has a larger size than

$Be$ and

$Mg. \ Ca$ is also larger in size compared to

$Na$ because it has a higher number of electrons that are present farther from the nucleus.

So, calcium (

$Ca$ ) is the largest size among given atoms.

Hence, the correct option is

$\text{A}$ .

Hydrogen combines with chlorine to form HCI. It also combines with sodium to form NaH. If sodium and chlorine also combine with each other, they will do so in the ratio of their masses as:

0%
23 : 35.5
0%
35.5 :23
0%
1 : 1
0%
23 : 1

Explanation

Since, mass ratio of

$H : Cl = 1 : 35.5$ in HCl and

$Na : H = 23 : 1$ in NaH.
And since according to law of constant proportion compounds always contains its elements in a fixed ratio by mass.
So, for

$\text{ 1gm of H}$ we are having

$\text{ 35.5gm Cl and 23gm Na.}$
Hence, the ratio

$Na : Cl = 23 : 35.5$ .
Hence, the answer is option A.

Atomic size is of the order of____________.

0%
${10}^{-7} cm$
0%
${10}^{-10} cm$
0%
${10}^{-13} cm$
0%
${10}^{-6} cm$

Explanation

The atomic size or atomic radius is of the order of

$\displaystyle {10}^{-7} cm$ or

$\displaystyle {10}^{-9} m$ or 1 nanometer(nm).

$SO_2$ gas was prepared by
(i) burning sulphur in oxygen,
(ii) reacting sodium sulphite with dilute

$H_2SO_4$ and
(iii) heating copper with

$conc. H_2SO_4$ . It was found that in each case sulphur and oxygen combined in the ratio of 1 :The data illustrates the law of :

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

Explanation

Ratio of sulfur & oxygen

$=1:1.$

Thus illustrates law of constant proportions because the ratio is a constant.

$1$ mole of a compound contains

$1$ mole of

$C$ and

$2$ moles of

$O$ . The molecular weight of the compound is :

0%
3
0%
12
0%
32
0%
44

Explanation

Given that :

1 mole of compound contains 1 mole of

$C$ and 2 moles of

$O$ .

Therefore, the molecular formula of the compound is

$C_{1}O_{2}$ .

$\Rightarrow$ Molecular Formula of the compound

$= CO_{2}$

Molecular weight of the compound =

$1 \times 12$ (Molecular weight of the carbon)

$+ 2\times 16$ (Molecular weight )of the oxygen)

$= 12 + 32 = 44$

Molecular weight of the compound

$= 44g$

$\therefore$ Molecular weight of 1 mole of the compound

$= 44g$

Hence the correct option is D.

A sample of

$CaCO_3$ has Ca - 40%, C = 12% and O = 48%. If the law of constant proportions is true, then the mass of Ca in 5 g of

$CaCO_3$ from another source will be:

0%
2.0 g
0%
0.2 g
0%
0.02 g
0%
20.0 g

Explanation

Since, mass percentage of Ca in

$CaCO_3 = 40 \text{%}$ and law of constant proportion is true.
So, the mass percentage of

$Ca$ in

$5gm$

$CaCO_3$ will also be

$40\text%.$

Hence,

$40\text{% of 5gm =}$

$5\times$

$\dfrac{40}{100}$

$= 2gm$

Hence, answer is option A.

The number of electrons in one molecule of

$CO_{2}$ are:

0%
$22$
0%
$44$
0%
$66$
0%
$88$

Explanation

One molecule of

$CO_2$ have

$22$ electrons.

$C + O+ O\Rightarrow 6 + 8+ 8 =22$

If one mole contains

$1.0 \times 10^{24}$ particles, the mass of one mole of oxygen is:

0%
53.2 g
0%
5.32 g
0%
32.0 g
0%
16.0 g

Explanation

1 mole of oxygen contains

$\displaystyle 6.02 \times 10^{23}$ particles and its mass is 32 g.

If a mole was to contain

$1.0 \times 10^{24}$ particles, the mass of one mole of oxygen is

$\displaystyle \dfrac {32}{6.02 \times 10^{23}} \times 1.0 \times 10^{24} = 53.2$ g.

The charge on 1 gram of

$Al^{3+}$ ions is (e=electronic charge):

0%
$\dfrac{1}{27}N_Ae\, coulomb$
0%
$\dfrac{1}{3}N_Ae\, coulomb$
0%
$\dfrac{1}{9}N_Ae\, coulomb$
0%
$3\, N_Ae\, coulomb$

Explanation

So for finding the charge of one gram ion of $Al^{3+}$ , We have to know that

1 gm atom = 1 mole of atom

So, charge on one mole of electron = $N_a \times$ charge on $1 e^⁻$

Thus, Charge on one mole of $Al^{3+}$ ion $= 3 \times N_A \times e$

Since , 27 g of $Al^{3+}$ ion having charge of $3 \times N_A \times e$ .

Therefore, 1 g of $Al^{3+}$ ion having charge = $\cfrac{3 \times N_A \times e}{ 27}$ C.

$=\cfrac{ N_a e^⁻}{ 9} C$

Option C is correct.

Law of constant composition is same as the law of:

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

The haemoglobin from red corpuscles of most mammals contains approximately 0.33% of iron by weight. The molecular weight of haemoglobin is 67,The number of iron atoms in each molecule of haemoglobin is:

0%
1
0%
2
0%
3
0%
4

Explanation

$100g$ sample of hemoglobin contains 0.33 g iron

67200g sample of hemoglobin contains

$= 0.33\times67200/100 = 221.8g$

$\therefore$ number of iron atoms per molecule of hemoglobin

$= 221.8/56 = 4$

The number of electrons which will together weight one gram is :

0%
$1.098 \times 10^{27}$ electrons
0%
$9.1096\times 10^{31}$ electrons
0%
$1$ electron
0%
$1\times 10^4$ electrons

Explanation

Mass of one electron

$= 9.1096 \times 10^{−31}$ kg

Number of electrons

$\times$ mass of 1 electron

$= 1 g = 10^{−3} kg$

$N \times 9.1096 \times 10^{−31}=10^{-3}$

$N=\frac{10^{−3}}{9.1096 \times 10^{−31}}$

$N= 1.098 \times 10^{27}$ electrons

Option A is correct

The ratio of radius of the nucleus to the radius of the atom is of the order:

0%
$10^5$
0%
$10^6$
0%
$10^{-5}$
0%
$10^{-8}$

Explanation

Nuclear radius $=10^{-15}$ m

Atomic radius $= 10^{-10}$ m

Ratio $= \dfrac{10^{-15}}{ 10^{-10}}=10^{-5}$

Hence, the correct option is $C$

How many moles of oxygen gas can be produced during electrolytic decomposition of

$180 \ g$ of water?

0%
2.5 moles
0%
5 moles
0%
10 moles
0%
7 moles

Explanation

Water decomposition can be represented as:

$2H_2O \rightarrow 2H_2+O_2$

$2$ moles (or

$2\times 18=36$ g) of water gives one mole of oxygen.

$180$ g water will produce

$\dfrac{180}{36}$ mol of oxygen

$=5$ mol of oxygen.

Hence, option

$B$ is correct.

$X\ gm$

$A$ atoms on combining with

$Y$ atoms of

$B$ form 5 molecules of a compound containing

$A$ &

$B$ . Find the molecular weight of compound formed. (Atomic weight of

$B = M$ )

0%
$\dfrac { \left( X{ N }_{ A }+MY \right) }{ 5 }$
0%
$\dfrac { X+M }{ 5 } \\$
0%
$\dfrac { X+MY }{ 5 }$
0%
$\left( \dfrac { X+MY{ N }_{ A } }{ 5 } \right)$

Explanation

Molecular weight of compound formed be

$W$

$X+MY =5W$

$W= \dfrac{X+MY}{5}$

Which symbol is used to represent the unit of atomic mass, amu?

0%
u
0%
A
0%
M
0%
n

4.88 g of

$KClO_3$ when heated produced 1.92 g of

$O_2$ and 2.96 g of KCl. Which of the following statements regarding the experiment is correct?

0%
The result illustrates the law of conservation of mass.
0%
The result illustrates the law of multiple proportions.
0%
The result illustrates the law of constant proportion.
0%
None of the above laws is being illustrated here.

Explanation

$2KClO_3 \rightarrow 2KCl+3O_2$

Mass of the reactant = total mass of the products (

$2.96 + 1.92=4.88\ g$ )

According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants. Therefore, this demonstrates the law of conservation of mass.

Option A is correct

Which of the following statements best explains the law of conservation of mass, concerning a chemical change?

0%
100 g of water is heated to give steam.
0%
A sample of $N_2$ gas is heated at constant pressure without any change in mass.
0%
36 g of carbon combines with 32 g of oxygen to form 68 g of $CO_2$ .
0%
10 g of carbon is heated in vacuum without any change in mass.

Explanation

According to the law of conservation of mass, the mass of the products in a chemical reaction must equal the mass of the reactants.

Among the given option only option C involves a chemical change/reaction as:

$C+O_2 \rightarrow CO_2$

$m_{reactants}=m_{products}$

$36+32=68\ g$

option C is the best demonstration of the law of conservation of mass.

In an experiment,

$2.4\ g$ of iron oxide on reduction with hydrogen gave

$1.68\ g$ of iron. In another experiment,

$2.69\ g$ of iron oxide gave

$1.88 \ g$ of iron on reduction. Which law is illustrated from the above data?

0%
Law of constant proportions
0%
Law of multiple proportions
0%
Law of reciprocal proportions
0%
Law of conservation of mass

Explanation

In the first experiment,

$2.4\ g$ of iron oxide gave

$1.68\ g$ of iron.
Mass of iron oxide

$=2.4\ g$

Mass of iron

$=1.68\ g$

$\therefore$ Mass of oxygen

$=2.4-1.68=0.72$

The ratio of masses of iron and oxygen

$=\dfrac{1.68}{0.72}=7:3$

In the second experiment,

Mass of iron oxide

$=2.69\ g$

Mass of iron

$=1.88\ g$

Mass of oxygen

$=2.69-1.88=0.81$

The ratio of masses of iron and oxygen

$=\dfrac{1.88}{0.81}=7:3$

The same ratio confirms that these experiments clarify Law of constant proportion.

Hence, option

$A$ is correct.

Decreasing order of atomic weight is correct of the elements given below?

0%
$Fe > Co > Ni$
0%
$Ni > Co > Fe$
0%
$Co > Ni > Fe$
0%
$Co > Fe > Ni$

Explanation

Atomic weight of Iron

$\approx 56$ u

Atomic weight of Cobalt

$\approx 59$ u

Atomic weight of Nickel

$\approx 58.7$ u

So, the order of atomic weights is

$Co>Ni>Fe$ .
Option

$C$ is correct.

Choose the correct answers from the alternative given.
Who among the following proposed that atom is indivisible?

0%
Dalton
0%
Berzelius
0%
Rutherford
0%
Avogadro

If water samples taken from the sea, rivers, lakes or snow-capped mountains, are found to contain hydrogen and oxygen in the ratio of

$1: 8$ . This demonstrates:

0%
The law of chemical equilibrium
0%
The law of definite proportions
0%
Avogadro's law
0%
The modern periodic law

How much copper is present in

$50\ g$ of

$CuSO_4$ ?

0%
$19.90\ g$
0%
$39.81\ g$
0%
$63.5\ g$
0%
$31.71\ g$

Explanation

Molar mass of

$CuSO_4=63.5+32+4 \times 16=159.5$ g

159.5 g

$CuSO_4$ contains 63.5 g Cu

50 g

$CuSO_4$ will have

$=\cfrac{63.5}{159.5} \times 50=19.90g\ Cu$

Fill in the blanks by choosing the correct options.

0%
$X= 6.023\times 10^{23}$ moleccules
$Y= 22.4L$ at any pressure
$Z=$ Gram molecular mass
0%
$X= 6.023\times 10^{23}$ atoms/moleccules
$Y= 22.4L$ at NTP
$Z=$ Gram atomic mass
0%
$X=6.023\times 10^{23}$ atoms
$Y= 22.4L$ at any temperature
$Z=1$ gram mole
0%

$X=6.023\times 10^{23}$ particles
$Y= 11.2L$ at NTP
$Z=$ Molar volume

Explanation

$1$ mole

$=6.023\times 10^{23}$ atoms / molecules

$=X$

$1$ mole = Molar volume

$=22.4\ L$ at

$NTP$

$=Y$

$1$ mole = Gram atomic mass or gram molecular mass

$=Z$

Hence, option

$B$ is correct.

The mass of one mole of a substance in gram is called its:

0%
molecular mass
0%
molar mass
0%
Avogadro's mass
0%
formula mass

Explanation

The mass of one mole of a substance in a gram is called its molar mass.

Hence, option

$B$ is correct.

Which of the following correctly represents 180 g of water?
(i) 5 moles of water
(ii) 10 moles of water
(iii)

$6.023 \times 10^{23}$ molecules of water
(iv)

$6.023 \times 10^{24}$ molecules of water

0%
(i)
0%
(ii)
0%
(iii)
0%
(iv)

Explanation

$18\ g$ of

$H_2O=1$ mol

$180\ g$ of

$H_2O=10$ mol

$18\ g$ of

$H_2O=6.023\times 10^{23}$ molecules of

$H_2O$

$180\ g$ of

$H_2O=\dfrac {6.023\times 10^{23}}{18}\times 180$

$=6.023\times 10^{24}$ molecules of

$H_2O$

The density of a gaseous substance at 1 atm pressure and 773 K is 0.4g/lit. If the molecular weight of the substance is 30 the forces existing among gas molecules are?

0%
repulsive
0%
attractive
0%
both
0%
none

Explanation

$PV = ZnRT$ or

$PM = ZdRT$ (

$M =$ molecular weight)

Now put all the given value

$(1)(30) = z(0.4)(0.082)(773)$

$z=0.074 < 1$ , thus forces are attractive.

Hence, option

$B$ is the correct answer.

The number of atoms present in

$16g$ of oxygen is:

0%
$6.02\times { 10 }^{ 15 }$
0%
$3.01\times { 10 }^{ 23 }$
0%
$3.01\times { 10 }^{ 15 }$
0%
$6.02\times { 10 }^{ 23 }$

Explanation

1 mole of oxygen

$=16g$

1 mole of oxygen contains

$=6.022\times { 10 }^{ 23 }\quad atoms$

$\therefore$

$16$ of oxygen

$=6.022\times { 10 }^{ 23 }\quad atoms$

Answer will be

$\left( D \right)$

What is the proportion of hydrogen and oxygen by weight in water?

0%
$1:16$
0%
$1:8$
0%
$16:1$
0%
$18:1$

Explanation

The weight of water is

$18$ amu.

Weight of oxygen

$=16$ amu

Weight of hydrogen

$=2$ amu

Thus, the ratio of Hydrogen : Oxygen is

$2:16=1:8$

Insulin contains 3.4% sulphur by mass. What will be minimum molecular weight of insulin?

0%
$94.117$
0%
$1884$
0%
$941.7$
0%
$976$

Explanation

The formula for mass percentage is given by:

$Mass\ percentage = \dfrac {mass\ of\ solute}{mass\ of\ solution}$

We need to find the molar mass of solution (insulin). We will take the molar mass of solute (sulphur)

$= 32\ g/mol$

Mass percentage is given as

$3.4\%$

Substituting these values in the formula gives:

$\dfrac {3.4}{100} = \dfrac {32}{mass\ of\ solution}$

Mass of solution (insulin)

$= \dfrac {32}{3.4}\times 100 = 941.7\ g/mol$

$0.1g \ CaCO_3$ will contain:

0%
$0.1 N_A \ Ca^{2-}\ ion$
0%
$0.01N_A \ Ca^{2+} \ ion$
0%
$0.001 N_A \ Ca^{2+}\ ion$
0%
$N_A\ Ca^{2+}\ ion$

Explanation

$CaCO_3 \longrightarrow Ca^{2+} + CO_3^{2-}$

$n$ mole of

$CaCO_3$ will give

$n$ mole of

$Ca^{2+}$ ion.

So Mole of

$CaCO_3$ = Mole of

$Ca^{2+}$

$\Rightarrow\dfrac{Given \ mass}{Molar \ mass} =$ Moles of

$Ca^{2+}$

$\Rightarrow\dfrac{.1}{100} =$ Mole of

$Ca^{2+}$

$\therefore$ Moles of

$Ca^{2+} = 0.001 \ mole$

Number of ions =

$N_A\times moles$

Number of ions =

$N_A\times .001$

Hence, option

$C$ is correct.

CBSE Questions for Class 9 Chemistry Atoms And Molecules Quiz 9 - MCQExams.com

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Practice Class 9 Chemistry Quiz Questions and Answers

CBSE Questions for Class 9 Chemistry Atoms And Molecules Quiz 9 - MCQExams.com

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Practice Class 9 Chemistry Quiz Questions and Answers

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