Atoms and Molecules Test

Result

Atoms and Molecules Test - 33

Score
-
out of -
Rank
-
out of -

TIME Taken - -

SHARING IS CARING

If our Website helped you a little, then kindly spread our voice using Social Networks. Spread our word to your readers, friends, teachers, students & all those close ones who deserve to know what you know now.

Weekly Quiz Competition

Question 1
1 / -0

$$1.2\, \times\, 10^{24}$$ atoms of iron weighs ______ grams.

A
$$90$$

B
$$111.5$$

C
$$80$$

D
$$70$$

Solution

For Fe atomic mass $$= 56$$ g $$= 6.023 \times (10 )^{ 23 }$$ atoms
$$1.2 \times { 10 }^{ 24 }$$ atoms $$=\quad \dfrac { 56 }{ 6.023\times { 10 }^{ 23 } } \times 1.2\times { 10 }^{ 24 }= 111.5$$g
Question 2
1 / -0

All samples of carbon dioxide contain carbon and oxygen in the mass ratio of $$3 : 8$$. This is in agreement with the law of :

A
conservation of mass

B
constant proportion

C
multiple proportions

D
gaseous volumes

Solution

LAW OF CONSTANT OR DEFINITE PROPORTION : It was given by Proust.
It states that all chemical compounds are found to have constant composition irrespective of their method of preparation or sources.
THE LAW OF MULTIPLE PROPORTION : It was given by Dalton.
It states that when one element combines with the other element to form two or more different compounds, the mass of one element which combines with a constant mass of the other bear a simple ratio to one another.
Question 3
1 / -0

An element A (atomic weight $$=12$$) and B (atomic weight $$=35.5$$) combines to form a compound X. If $$4$$ mol of B combines with $$1$$ mol of A to give $$1$$ mol of X. The weight of $$1$$ mol of X would be :

A
47.5 g

B
74.0 g

C
154.0 g

D
148.8 g

Solution

Given:
Atomic weight of A= 12 and B= 35.5
A and B combine to form a compound X and the reaction can be given as:
$$\begin{array}{l}\;\;\;\:\:\:4B\;\;\;\;+\;\;A\;\rightarrow X\\4\times35.5\;+\;12\rightarrow\;?\end{array}$$
Weight of X = ($$4\times35.5$$) + $$12$$ = 154 g
So the correct option is C.
Question 4
1 / -0

Atomic mass of an element is:

A
actual mass of one atom of the element

B
average mass of an atom of different atoms of the element

C
always a whole number

D
None of these

Solution

Atomic mass is an average mass of different atoms of an element, as most elements have different isotopes. Atomic mass is usually not a whole number. It can be a fraction.
Question 5
1 / -0

Law of conservation of mass was put forward by :

A
Lavoisier

B
Dalton

C
Priestly

D
Thomson

Solution

The Law of conservation of mass was put forward by Russian scientist Lomonosov in the year 1765. Later in 1783, French scientist Antoine Lavoisier also stated the same law independently.
Question 6
1 / -0

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

A
26.07 g

B
2.607

C
260.7

D
None

Solution

$$100$$ g of compound contains $$5.37$$ g of nitrogen.
$$\therefore$$The number of moles of nitrogen is $$\dfrac {5.37}{14}=0.3835 $$ moles.
Hence, the minimum molecular weight of the compound is $$\dfrac {100}{0.3835}=260.7$$ g/mol.
Option $$C$$ is correct.
Question 7
1 / -0

An organic compound contains $$4$$% sulphur. Its minimum molecular weight is :

A
200

B
400

C
800

D
1600

Solution

$$4$$g sulphur is in $$100$$ g compound, hence $$32$$ g sulphur is in $$=\left (\frac {100}{4}\times 32\right )=800 g$$ compound.
Question 8
1 / -0

Which of the following options contains only elements?

A
Air, water, oxygen

B
Hydrogen, oxygen, brass

C
Air, water, iron

D
Calcium, sulphur, carbon

Solution

Option A: Only oxygen is an element, air is a mixture of gases and water is a compound.

Option B: Hydrogen and oxygen are elements, but brass is an alloy hence a homogeneous mixture.

Option C: Only iron is an element.

Option D: Calcium, sulphur, and carbon are elements and hence the answer.
Question 9
1 / -0

The smallest particle of a substance (element or compound) which has the properties of that substance and can exist independently is called a ..............

A
Molecule

B
Atom

C
Nucleus

D
Neutrons

Solution

The smallest particle of a substance (element or compound) which has the properties of that substance and can exist independently is called a $$molecule$$.
Question 10
1 / -0

Which of the following is true for the molecules of gases?

A
They have a fixed volume.

B
They have a fixed shape.

C
They cannot move freely.

D
They can move around freely.

Solution

A gas is composed of molecules that are in constant random motion. It does not have a fixed volume as it can expand to fill available space. Also, it has no fixed shape and will take the shape of the container it is in. The intermolecular forces of attraction between gas molecules are very minute. That's why they move around freely.

User

Question Analysis

Correct -
Wrong -
Skipped -

My Perfomance

Score
-
out of -
Rank
-
out of -

Re-Attempt Weekly Quiz Competition

Atoms and Molecules Test - 33

Result

Atoms and Molecules Test - 33

Score

-

Rank

-

SHARING IS CARING

Question 1

$$90$$

$$111.5$$

$$80$$

$$70$$

Solution

Question 2

conservation of mass

constant proportion

multiple proportions

gaseous volumes

Solution

Question 3

47.5 g

74.0 g

154.0 g

148.8 g

Solution

Question 4

actual mass of one atom of the element

average mass of an atom of different atoms of the element

always a whole number

None of these

Solution

Question 5

Lavoisier

Dalton

Priestly

Thomson

Solution

Question 6

26.07 g

2.607

260.7

None

Solution

Question 7

200

400

800

1600

Solution

Question 8

Air, water, oxygen

Hydrogen, oxygen, brass

Air, water, iron

Calcium, sulphur, carbon

Solution

Question 9

Molecule

Atom

Nucleus

Neutrons

Solution

Question 10

They have a fixed volume.

They have a fixed shape.

They cannot move freely.

They can move around freely.

Solution

User

Question Analysis

My Perfomance

Score

-

Rank

-

Results Announcement on: coming Monday

Stay Tuned: We’ll update you on your result via email or SMS.