Atoms and Molecules Test

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Atoms and Molecules Test - 46

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Weekly Quiz Competition

Question 1
1 / -0

Formula unit mass of magnesium chloride is :

A
94

B
95

C
96

D
24

Solution

Formula unit mass of magnesium chloride ($$MgCl_2$$) is $$24+35.5+35.5=95$$
Question 2
1 / -0

______ are the smallest unit of matter that can take part in a chemical reaction.

A
Molecules

B
Compounds

C
Atoms

D
Electrons

Solution

Dalton's atomic theory states that atoms are the smallest unit of matter that can participate in a chemical reaction. Chemical reactions involve the combination, separation, or rearrangement of atoms, but atoms are neither created, destroyed, divided into parts, or converted into atoms of any other kind.
Option $$C$$ is correct.
Question 3
1 / -0

Atomic mass of which of the following element is $$24$$?

A
Magnesium

B
Sodium

C
Chlorine

D
Sulphur

Solution

Atomic mass of magnesium is $$24$$.
Question 4
1 / -0

Find the mass of $$4.12\times 10^{24}$$ molecules of $$NH_3$$?

A
$$110\ g$$

B
$$116.3\ g$$

C
$$120\ g$$

D
$$100\ g$$

Solution

Number of Moles $$= \dfrac{Given \ number \ of \ molecules}{N_A}$$

Number of Moles of $$ NH_3=\dfrac{4.12\times 10^{24}}{6.022\times 10^{23}}=6.84$$

Mass of one mole of $$NH_3 = 17 \ g\ (molar \ mass)$$

Mass of $$6.84 \ moles \ of\ NH_3=6.84\times 17\ g=116.3\ g\ (approximately)$$
Question 5
1 / -0

Who believed that atoms could not be split?

A
Thomson

B
Rutherford

C
Dalton

D
Both A and B

Solution

Dalton believed matter to be made up of tiny indivisible particles called atoms.
Both Thomson and Rutherford considered the presence of charged species in an atom and did not believe in the indivisibility of atom.
So, option C is correct.
Question 6
1 / -0

Who postulated that matter is made up of very small particles in 430 BC?

A
Democritus

B
Aristotle

C
Dalton

D
Robert Brown

Solution

Democritus postulated that matter is made up of very tiny particles i.e atom. In approximately 430 B.C. Democritus coined the term atoms, which means “un-cuttable” or “the smallest indivisible particle of matter. They are homogeneous, contain no void and no interstices, and are in perpetual motion moving equally in all directions.
Question 7
1 / -0

When two molecules of hydrogen react with one molecule of oxygen, the mass of reactants is $$36$$, what is the mass of products?

A
$$18$$

B
$$36$$

C
$$9$$

D
$$32$$

Solution

The Law of conservation of mass states that the total mass of reactants is equal to the total mass of products. In any chemical reaction, the total mass of the substance before and after the reaction is the same although its matter undergoes a physical change.

$$2H_2+O_2 \longrightarrow 2H_2O$$

Hence, the mass of the product i.e., water is $$36$$.
Question 8
1 / -0

J.J. Thomson discovered _________ at the end of 19th century.

A
Electrons

B
Nuclei

C
Atoms

D
Molecules

Solution

J.J. Thomson's discovery of the electron in 1897 showed us that the atom can be split into even smaller parts. His discovery was the first step towards a detailed model of the atom.
Question 9
1 / -0

Who proposed the earliest views on the shapes and connectivity of atoms?

A
Leucippus

B
Rutherford

C
Thomson

D
Both B and C

Solution

The earliest views on the shapes and connectivity of atoms were proposed by Leucippus, Democritus, and Epicurus who reasoned that the solidness of the material corresponded to the shape of the atoms involved.
Question 10
1 / -0

The theory of Democritus state that:

A
everything is composed of "atoms", which are physically, but not geometrically, indivisible

B
between atoms, there lies empty space

C
there are an infinite number of atoms

D
All of the above

Solution

Atoms and void are the bases of Democritus system for explaining the universe: solid indestructible atoms, infinite in number and shape, differing in size, but otherwise lacking in sensible qualities, were originally scattered throughout infinite void. In general, the atoms were so small as to be invisible. Atomos means that the atoms are physically indivisible.

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Re-Attempt Weekly Quiz Competition

Atoms and Molecules Test - 46

Result

Atoms and Molecules Test - 46

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SHARING IS CARING

Question 1

94

95

96

24

Solution

Question 2

Molecules

Compounds

Atoms

Electrons

Solution

Question 3

Magnesium

Sodium

Chlorine

Sulphur

Solution

Question 4

$$110\ g$$

$$116.3\ g$$

$$120\ g$$

$$100\ g$$

Solution

Question 5

Thomson

Rutherford

Dalton

Both A and B

Solution

Question 6

Democritus

Aristotle

Dalton

Robert Brown

Solution

Question 7

$$18$$

$$36$$

$$9$$

$$32$$

Solution

Question 8

Electrons

Nuclei

Atoms

Molecules

Solution

Question 9

Leucippus

Rutherford

Thomson

Both B and C

Solution

Question 10

everything is composed of "atoms", which are physically, but not geometrically, indivisible

between atoms, there lies empty space

there are an infinite number of atoms

All of the above

Solution

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