Atoms and Molecules Test

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Atoms and Molecules Test - 51

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Weekly Quiz Competition

Question 1
1 / -0

Statement 1: One mole of $$CO_2$$ has a greater mass than $$1$$ mole of $$H_2O$$.
Statement 2: The molecular mass of $$CO_2$$ is greater than the molecular mass of $$H_2O$$.

A
Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1

B
Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1

C
Statement 1 is correct but Statement 2 is not correct

D
Statement 1 is not correct but Statement 2 is correct

E
Both statements are incorrect

Solution

Statement 1: One mole of $$CO_2$$ has a greater mass than $$ 1$$ mole of $$H_2O$$.

Statement 2: The molecular mass of $$CO_2$$ is greater than the molecular mass of $$H_2O$$.

The molecular masses of $$CO_2$$ and $$H_2O$$ are $$44\ g/mol$$ and $$18 \ g/mol$$ respectively.

The mass of $$1$$ mole of a substance is equal to its molecular mass.
Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1.
Hence, option $$A$$ is correct.
Question 2
1 / -0

Find the accurate statement for the significance of Avogadro's number ?

A
It is the conversion factor between grams and pounds.

B
It is a universal physical constant just as the speed of light.

C
It is the number of particles that is required to fill a 1-liter container.

D
It is the inverse diameter of an H atom.

E
It is the number of electrons in the universe.

Solution

Avogadro's number is a universal physical constant just as the speed of light.
Avogadro's number represents the number of atoms/ molecule present in 1 mole of any substance.
Question 3
1 / -0

All atoms of the same element have :

A
different numbers of electrons.

B
equal number of protons.

C
different numbers of neutrons.

D
different numbers of protons.

E
equal number of neutrons.

Solution

Atoms of the same element have the same atomic number so the number of protons (and electrons) are same. But they have same or different mass numbers (like that for isotopes). Different mass number will have different number of neutrons.
Question 4
1 / -0

Molar mass of ethanol $$(C_2H_5OH)$$ is:
(Atomic masses: C = 12 u, H = 1 u, O = 16 u)

A
$$34$$

B
$$38.9$$

C
$$46$$

D
$$45.1$$

E
$$62.1$$

Solution

Molar mass of ethanol ($$C_2H_5OH$$) $$=\displaystyle ( 2 \times atomic\ mass\ of\ carbon) + (6 \times atomic\ mass\ of\ hydrogen) + (1 \times atomic\ mass\ oxygen)$$

$$=\displaystyle 2(12) + 6(1) + 1(16) = 46\ g/mol$$
Question 5
1 / -0

How many atoms are represented by the formula $$\displaystyle { K }_{ 3 }{ Fe\left( CN \right) }_{ 6 }$$ ?

A
6

B
10

C
16

D
20

E
18

Solution

K atoms- 3
Fe atoms- 1
C atoms - 6
N atoms - 6
Total atoms in compound - 16
Question 6
1 / -0

Who first coined the term 'atomos' meaning indivisible?

A
Rutherford

B
Thomson

C
Aristotle

D
Democritus

E
Dalton

Solution

'Atomos' is a Greek term for 'atom'. Coined by the Greek philosopher, Democritus, the word 'atomos' means indivisible. Democritus believed that matter is made of tiny particles (atoms) that cannot be divided or cut any further.
Question 7
1 / -0

$$0.25$$ moles of $$O_2$$ at STP equal to_____.

A
$$9.03\times10^{23}$$ molecules

B
$$44.8 $$ liters

C
$$3.5$$ moles

D
$$6.0$$ grams

E
$$3.01\times10^{23}$$ atoms

Solution

$$1$$ mole of $$O_2$$ molecule = $$2 \ 'O'$$ atoms
$$0.25$$ moles of $$ O_2$$ molecules $$= \displaystyle 2 \times 0.25 = 0.50$$ moles of $$O$$ atoms.
$$1$$ mole of $$O$$ atoms is equal to avogadro's number $$6.023 \times 10^{23}$$ of atoms
$$0.50$$ moles of $$O$$ atoms is equal to $$\displaystyle 6.023 \times 10^{23} \times 0.5 = 3.01 \times 10^{23}$$ $$O$$ atoms.
Hence, option E is correct.
Question 8
1 / -0

The molar mass of $$CaCO_3$$ is :

A
$$68$$ g$$/$$mol

B
$$75$$ g$$/$$mol

C
$$82$$ g$$/$$mol

D
$$100$$ g$$/$$mol

E
$$116$$ g$$/$$mol

Solution

Molar mass of $$Ca$$ is $$40 \ g/mole$$
Molar mass of $$C$$ is $$12 \ g/mole$$
Molar mass of $$O$$ is $$16 \ g/mole$$
Total molar mass is $$40+12+16 \times 3 =100\ g/mol$$
Question 9
1 / -0

Which of the groups below represents the correct relationship in order from smallest (or simplest) to largest (or more complex)?

A
Matter - element - compound - electron - atom

B
Electron - element - atom - compound - matter

C
Electron - atom - element - matter - compound

D
Electron - atom - element - compound - matter

E
Atom - electron - element - compound - matter

Solution

Electrons, protons, and neutrons are the smallest particles of atoms. Elements are one of the basic substances that are made of atoms of only one kind and that cannot be separated by ordinary chemical means into simpler substances. A chemical compound is an entity consisting of two or more atoms, at least two from different- elements; which associate via chemical bonds. Atoms and molecules are all composed of matter. The matter is anything that has mass and takes up space.
So correct order from lowest to highest is Electron - atom - element - compound - matter.
Question 10
1 / -0

Which of the following will not be affected by changes in temperature and pressure?

A
Density

B
Equilibrium constant

C
Molar mass

D
Freezing point

E
Molarity

Solution

Properties are affected by a change in temperature and pressure.
For example, the phase of a substance is determined by its temperature and pressure, the density of fluid changes with temperature and pressure. Molarity is defined as the number of moles of solute dissolved per liter of solution. It is expressed in units as $$mol/L$$. Molar mass is the mass of one mole of substances. It does not change with temperature and pressure. All other properties like density, melting point, the equilibrium constant are temperature or pressure-dependent.

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Atoms and Molecules Test - 51

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Atoms and Molecules Test - 51

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Question 1

Both Statement 1 and Statement 2 are correct and Statement 2 is the correct explanation of Statement 1

Both Statement 1 and Statement 2 are correct and Statement 2 is not the correct explanation of Statement 1

Statement 1 is correct but Statement 2 is not correct

Statement 1 is not correct but Statement 2 is correct

Both statements are incorrect

Solution

Question 2

It is the conversion factor between grams and pounds.

It is a universal physical constant just as the speed of light.

It is the number of particles that is required to fill a 1-liter container.

It is the inverse diameter of an H atom.

It is the number of electrons in the universe.

Solution

Question 3

different numbers of electrons.

equal number of protons.

different numbers of neutrons.

different numbers of protons.

equal number of neutrons.

Solution

Question 4

$$34$$

$$38.9$$

$$46$$

$$45.1$$

$$62.1$$

Solution

Question 5

6

10

16

20

18

Solution

Question 6

Rutherford

Thomson

Aristotle

Democritus

Dalton

Solution

Question 7

$$9.03\times10^{23}$$ molecules

$$44.8 $$ liters

$$3.5$$ moles

$$6.0$$ grams

$$3.01\times10^{23}$$ atoms

Solution

Question 8

$$68$$ g$$/$$mol

$$75$$ g$$/$$mol

$$82$$ g$$/$$mol

$$100$$ g$$/$$mol

$$116$$ g$$/$$mol

Solution

Question 9

Matter - element - compound - electron - atom

Electron - element - atom - compound - matter

Electron - atom - element - matter - compound

Electron - atom - element - compound - matter

Atom - electron - element - compound - matter

Solution

Question 10

Density

Equilibrium constant

Molar mass

Freezing point

Molarity

Solution

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