Atoms and Molecules Test

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Atoms and Molecules Test - 47

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Weekly Quiz Competition

Question 1
1 / -0

Who called the indivisible particles as atoms?

A
Antoine L. Lavoisier

B
Democritus

C
Rutherford

D
Both B and C

Solution

In $$430 \ B.C$$, Democritus postulated that matter is made up of very small particles called “atoms” which means"indivisible".
Question 2
1 / -0

Which of the following structural feature of an atom was proposed by Rutherford?

A
The positively charged particle is called a proton.

B
The size of the nucleus is very small as compared to the size of the atom.

C
An atom consists of a positively charged sphere and the electrons are embedded in it.

D
All of above
Solution
On the basis of the gold foil experiment, Rutherford proposed structural features of the atom:
The positively charged center in an atom is called the nucleus. Nearly all the mass of an atom resides in the nucleus.
The electrons revolve around the nucleus in circular paths.
The size of the nucleus is very small as compared to the size of the atom.
Question 3
1 / -0

Which law is not applicable for a nuclear reaction where large amount of energy is released?

A
Law of conservation of mass

B
Law of definite proportion

C
Law of multiple proportion

D
Avagrado's law

Solution

The law implies that during any chemical reaction, nuclear reaction, or radioactive decay in an isolated system, the total mass of the reactants or starting materials must be equal to the mass of the products. Mass conservation remains correct if energy is not lost but if energy is released in a nuclear reaction, the law of conservation of mass does not hold any good.
Question 4
1 / -0

The formula unit mass of a substance is the:

A
sum of the atomic masses of all atoms in a formula unit of a compound

B
relative atomic masses of atoms

C
double the numerical value of the atomic mass

D
None of above

Solution

The formula mass of a substance is defined as the sum of the atomic masses of constituent atoms in a compound. This is generally used for compounds which do not contain discrete molecules, but ions as their constituent units. Example: NaCl (sodium chloride) made of sodium and chlorine ions. Formula unit mass of NaCl = (1 $$\times$$ 23) + (1 $$\times$$ 35.5) = 58.5 u
Question 5
1 / -0

A formula unit indicates :

A
the highest whole number ratio of ions in a compound.

B
only the lowest whole number ratio of uncharged molecules in a compound.

C
the lowest whole number ratio of ions in a compound.

D
both A and B.

Solution

A formula unit in chemistry is the empirical formula of any ionic compound. It is the lowest whole number ratio of ions represented in an ionic compound.
Question 6
1 / -0

Molecules made up of two or more elements are called:

A
ions

B
compounds

C
mixture

D
both a and c

Solution

A substance consisting of atoms or ions of two or more different elements in definite proportions joined by chemical bonds into a molecule is known as compound. The elements cannot be separated by physical means. Water, for example, is a compound having two hydrogen atoms and one oxygen atom per molecule.
Question 7
1 / -0

Which of the following element is represented by the chemical symbol $$P$$ ?

A
Sulphur

B
Phosphorus

C
Oxygen

D
Hydrogen

Solution

The symbol, $$\ P$$, represents the element Phosphorus.
Sulphur is represented by the symbol $$\ S$$.
Oxygen is represented by the symbol$$\ O$$.
Hydrogen is represented by the symbol$$\ H$$.
Question 8
1 / -0

Which of the following is not a property of a molecule?

A
Molecules of any given substance are similar.

B
Molecules are represented by chemical formula.

C
The properties of a substance are the properties of the molecule.

D
None of above.

Solution

All the above statements are properties of molecule. Molecules of any given substance are similar. Molecules of different substances are different. Molecules are represented by their chemical formula. The properties of a substance are shown by its individual molecules as well.

A molecule can be defined as the smallest particle of an element or a compound that is capable of an independent existence and shows all the properties of that substance.
Question 9
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A molecule is _________ .

A
Positive

B
Negative

C
Neutral

D
Both A and C

Solution

A group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction is known as a molecule. A molecule is an electrically neutral group of two or more atoms held together by chemical bonds. Molecules are made up of atoms that are held together by chemical bonds. These bonds are formed by sharing or exchange of electrons among atoms.

So, the correct option is $$C$$
Question 10
1 / -0

Formula unit mass is used for :

A
molecules

B
ionic compound

C
uncharged compounds

D
all of above

Solution

The formula mass of a substance is defined as the sum of the atomic masses of constituent atoms in an ionic compound. This is generally used for ionic compounds, which do not contain discrete molecules, but ions as their constituent units. Hence option B is correct.

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Atoms and Molecules Test - 47

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Atoms and Molecules Test - 47

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Question 1

Antoine L. Lavoisier

Democritus

Rutherford

Both B and C

Solution

Question 2

The positively charged particle is called a proton.

The size of the nucleus is very small as compared to the size of the atom.

An atom consists of a positively charged sphere and the electrons are embedded in it.

All of above

Solution

Question 3

Law of conservation of mass

Law of definite proportion

Law of multiple proportion

Avagrado's law

Solution

Question 4

sum of the atomic masses of all atoms in a formula unit of a compound

relative atomic masses of atoms

double the numerical value of the atomic mass

None of above

Solution

Question 5

the highest whole number ratio of ions in a compound.

only the lowest whole number ratio of uncharged molecules in a compound.

the lowest whole number ratio of ions in a compound.

both A and B.

Solution

Question 6

ions

compounds

mixture

both a and c

Solution

Question 7

Sulphur

Phosphorus

Oxygen

Hydrogen

Solution

Question 8

Molecules of any given substance are similar.

Molecules are represented by chemical formula.

The properties of a substance are the properties of the molecule.

None of above.

Solution

Question 9

Positive

Negative

Neutral

Both A and C

Solution

Question 10

molecules

ionic compound

uncharged compounds

all of above

Solution

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