Atoms and Molecules Test

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Atoms and Molecules Test - 35

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Weekly Quiz Competition

Question 1
1 / -0

14 g of element X combine with 16 g of oxygen. On the basis of this information, which of the following is a correct statement?

A
The element X could have an atomic weight of 7 and its oxide is XO.

B
The element X could have an atomic weight of 14 and its oxide is $$X_2O$$.

C
The element X could have an atomic weight of 7 and its oxide is $$X_2O$$

D
The element X could have an atomic weight of 16 and its oxide is $$X_2O$$

Solution

The atomic weight of oxygen is 16. The atomic weight of the element $$X$$ can be either 7 or 14.

One mole of the oxide will contain one mole (16 g) of oxygen atoms and one mole (14 g, if atomic weight of $$X$$ is 14) of $$X$$ atoms. Its formula will be $$XO$$.

One mole of the oxide will contain one mole (16 g) of oxygen atoms and two moles (14 g, if atomic weight of $$X$$ is 7) of $$X$$ atoms. Its formula will be $$ X_2{O}.$$

Thus option C is the correct answer.
Question 2
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A chemical equation is balanced in accordance with the law of

A
conservation of mass

B
multiple proportion

C
constant proportion

D
reciprocal proportion

Solution

There must be the same number of each element on both side of the chemical equation. It adheres with the conservation of mass.
Option $$A$$ is correct.
Question 3
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"All matter is made up of very small particles which cannot be further broken down. These particles are called atoms". This statement is one of the assumptions of :

A
Rutherford's nuclear theory

B
Bohr's theory

C
Dalton's atomic theory

D
Kinetic theory of gases

Solution

All matter is made up of very small particles which cannot be further broken down. These particles are called atoms". This statement is one of the assumptions of Dalton's atomic theory.
Question 4
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One mole of any substance contains $$6.023\times10^{23}$$ particles. It was determined by

A
Berzilius

B
Avogadro

C
Dalton

D
Perin

Solution

Avogadro's law states that in one mole of any substance, a total number of $$6.023 \times 10^{23}$$ molecules are present.
So, option $$B$$ is correct.
Question 5
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Which atom contains exactly 15 neutrons?

A
$$P^{32}$$ (atomic number $$= 17$$)

B
$$S^{32}$$ (atomic number $$= 16$$)

C
$$O^{15}$$ (atomic number $$= 8$$)

D
$$N^{15}$$ (atomic number $$= 7$$)

Solution

$$mass\space number= no. of \space protons + no. of\space neutrons$$
Given that mass number of P = 32
Atomic number (no. of electrons $$=$$ no. of protons) $$=$$ 17
Number of neutrons $$= 32 - 17 = 15$$
Hence, P satisfies the requirement.
Question 6
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Weight of oxygen in $$Fe_2O_3$$ and FeO is in the ratio of :

A
$$3 : 2$$

B
$$1 : 2$$

C
$$2 : 1$$

D
$$3 : 1$$

Solution

$$ Fe_2O_3 $$ = $$48g$$ oxygen
$$FeO = 16g$$ oxygen
ratio of oxygen in $$ Fe_2O_3$$ :oxygen in$$ FeO = 3:1$$
Question 7
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The percentage of copper and oxygen in a sample of CuO obtained from different methods were found to be same. This proves the law of :

A
Constant proportion

B
Multiple proportion

C
Reciprocal proportion

D
None of these

Solution

The percentage of copper and oxygen in a sample of CuO obtained from different methods were found to be same. This proves the law of Constant proportion as the ratio of Cu:O remains constant
Question 8
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The difference between ions and atoms is of :

A
relative size

B
electronic configuration

C
presence of charge

D
All of the above
Solution
An ion is a particle or collection of particles with a net positive or negative charge.

An atom is the basic unit of an element. The identity of an element is determined by the number of positively charged protons in atoms nucleus.

The difference between ions and atoms is of:
- Relative size
- Electronic configuration
- Presence of charge
Question 9
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An ionic compound of element $$M$$ and chlorine has the formula $$MCl_3$$, the molecular mass of $$MCl_3$$ is 118.5 u. What is the molecular mass of the oxide of an element $$M$$?

A
28

B
44

C
72

D
99
Question 10
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Amongst the following, which has the highest molecular mass?

A
$$Cl_2$$

B
$$N_2$$

C
$$CH_3OH$$

D
$$NH_3$$

Solution

The molecular masses of various compounds can be calculated as:

(i) $$Cl_{2}$$ ; $$2\times 35.5$$ $$=$$ $$71 g/mol$$

(ii) $$ N_{2}$$ ; $$2\times 14$$ $$=$$ $$28 g/mol$$

(iii) $$CH_{3}OH$$ ; $$12 + 3\times 1 + 16 + 1$$ $$=$$ $$32 g/mol$$

(iv) $$NH_{3}$$ ; $$14 + 3\times 1$$ $$=$$ $$17 g/mol$$

Thus $$Cl_{2}$$ molecule has the highest molecular mass of $$71$$ moles.

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Atoms and Molecules Test - 35

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Atoms and Molecules Test - 35

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Question 1

The element X could have an atomic weight of 7 and its oxide is XO.

The element X could have an atomic weight of 14 and its oxide is $$X_2O$$.

The element X could have an atomic weight of 7 and its oxide is $$X_2O$$

The element X could have an atomic weight of 16 and its oxide is $$X_2O$$

Solution

Question 2

conservation of mass

multiple proportion

constant proportion

reciprocal proportion

Solution

Question 3

Rutherford's nuclear theory

Bohr's theory

Dalton's atomic theory

Kinetic theory of gases

Solution

Question 4

Berzilius

Avogadro

Dalton

Perin

Solution

Question 5

$$P^{32}$$ (atomic number $$= 17$$)

$$S^{32}$$ (atomic number $$= 16$$)

$$O^{15}$$ (atomic number $$= 8$$)

$$N^{15}$$ (atomic number $$= 7$$)

Solution

Question 6

$$3 : 2$$

$$1 : 2$$

$$2 : 1$$

$$3 : 1$$

Solution

Question 7

Constant proportion

Multiple proportion

Reciprocal proportion

None of these

Solution

Question 8

relative size

electronic configuration

presence of charge

All of the above

Solution

Question 9

28

44

72

99

Question 10

$$Cl_2$$

$$N_2$$

$$CH_3OH$$

$$NH_3$$

Solution

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