Some Basic Concepts of Chemistry Test

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Some Basic Concepts of Chemistry Test - 22

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Weekly Quiz Competition

Question 1
1 / -0

Assertion : 20 gm of argon (atomic mass of Ar $$=40)$$ occupies volume of $$22400\ cm^3$$ at STP.
Reason : 20 gm of Neon (atomic mass of $$Ne=20$$) occupies a volume of $$22400\ cm^3$$ at STP.

A
Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

B
Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

C
Assertion is correct but Reason is incorrect.

D
Assertion is incorrect but Reason is correct.

E
Both assertion and reason are incorrect.

Solution

20 g of argon is 0.5 moles and it occupies $$(0.5\times 22400=)11200\ cm^3$$ at STP.
20 g of Neon is 1 mole and occupies a volume of $$22400\ cm^3$$ at STP.
Question 2
1 / -0

The volume occupied by half a mole of a gas at STP is:

A
5.6 L

B
11.2 L

C
22.4 L

D
44.8 L

Solution

The volume occupied by 1 mole of any gas is 22.4 litres.

So the volume occupied by half a mole of gas would be half of 22.4 litres.

So it will be $$11.2\ litres$$.

Hence, option B is correct.
Question 3
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Ethane burning in oxygen to give carbon dioxide and steam. The volume ratio of reactants to products is ______________.

A
2 : 6 : 4 : 3

B
2 : 7 : 2 : 5

C
3 : 4 : 4 : 6

D
2 : 7 : 4 : 6

Solution

The equation for the combustion reaction of ethane can be written as :
$$2C_{2}H_{6} + 7O_{2} \rightarrow 4CO_{2} + 6H_{2}O$$
Therefore the volume ratio of reactants and products $$= 2 : 7 : 4 : 6$$
Question 4
1 / -0

What is the mass of one atom of $$C-12$$ in grams?

A
1.992$$\displaystyle \times 10^{-23}$$ gm

B
1.989$$\displaystyle \times 10^{-23}$$ gm

C
1.892$$\displaystyle \times 10^{-23}$$ gm

D
1.965$$\displaystyle \times 10^{-23}$$ gm

Solution

Mass of $$1$$ mole = $$12\,gm$$

Mass of $$6.022 \times 10^{23}\,atom = 12\,gm$$

mass of $$1$$ atom = $$\dfrac{12}{6.023 \times 10^{23}} = 1.993 \times 10^{-23}\,gm$$
Question 5
1 / -0

A neutral atom of an element has a nucleus with a nuclear charge 13 times and mass 27 times that of hydrogen nucleus. What is the ratio of electrons to protons in its stable positively charged ion?

A
27 : 13

B
10 : 19

C
10 : 13

D
10 : 14

Solution

Let the neutral atom of the element be $$X$$.

Given, the nuclear charge of $$X$$ is 13 times that of the hydrogen nucleus.
$$\Rightarrow$$ Atomic number $$=13$$

Mass of X is 27 times that of hydrogen nucleus $$\Rightarrow $$ Mass number $$=27$$.

Since $$_{13}X^{27}, EC=2, 8, 3$$

If X forms stable positively charged ion i.e., $$X^{+3}$$ (as it has 3 valence electrons in its valence shell)

$$X^{+3}\rightarrow$$ Atomic number $$=13-3=10.$$ This implies number of electrons $$=10$$. Number of protons $$=13$$.

$$Ratio=10 : 13$$
Question 6
1 / -0

Barium chloride reacts with sodium sulphate to form Barium sulphate and sodium chloride. Then, according to the law of conservation of mass:

A
the total mass of reactants, barium chloride, and sodium sulphate taken is greater than the total mass of products, barium sulphate, sodium chloride formed

B
the total mass of reactants, barium chloride, and sodium sulphate is less than the total mass of products, barium sulphate, and sodium chloride

C
the total mass of the reactants is equal to the total mass of products

D
none of the above

Solution

The law of conservation of mass states that mass can neither be created nor be destroyed, it can only change from one form to the other.
So, according to the law, the amount of reactants consumed should be equal to the amount of the products formed.
Hence option C is correct.
Question 7
1 / -0

Which law states that the total mass of the reactants is equal to the total mass of the products in a chemical reaction?

A
Law of constant proportions

B
Law of conservation of energy

C
Law of conservation of mass

D
Law of multiple proportions

Solution

Law of conservation of mass states that in a chemical reaction, the total mass of the product is equal to the total mass of the reactants.

For example
$$CaCO_3\rightarrow CaO+CO_2$$

The total mass of reactant $$CaCO_3$$
$$=40+12+(16\times 3)=100$$

The mass of $$CaO=40+16=56$$

Mass of $$CO_2=12+(16\times 2)=44$$

The total mass of products $$CaO+CO_2=56+44=100$$.

Hence the above example illustrates that the total mass of reactants $$=$$ total mass of products.
Question 8
1 / -0

One a.m.u. or one 'u' is equal to :

A
$$1.66053892 10^{-27} kg$$

B
$$1.66053892 10^{-29} kg$$

C
$$1.23457656 10^{-27} kg$$

D
$$1.23457656 10^{-29} kg$$

Solution

One a.m.u.(atomic mass unit) or one 'u' is $$\dfrac{1}{12}$$ of the mass of one carbon-$$12$$ atom.
It is equal $$1.6605389210 \times 10^{-24} g $$ or $$1.6605389210 \times 10^{-27} kg$$.
Question 9
1 / -0

The modern atomic mass unit is based on the mass of :

A
C-12 isotope

B
hydrogen

C
oxygen

D
nitrogen

Solution

One a.m.u. or one 'u' is equal to $$1.66053892 10^{-24}\ g $$ or $$1.66053892 10^{-27}\ kg$$. It is equal to $$\dfrac{1}{12}$$ of the mass of an atom of carbon-12.

It is used as a standard. The masses of all other atoms are determined relative to the mass of an atom of carbon-12.
Question 10
1 / -0

If the fertilizers listed below are priced according to their nitrogen content, which will be the least expensive per $$50$$ kg bag?

A
Urea, $$(NH_2)_2CO$$

B
Ammonia, $$NH_3$$

C
Ammonium nitrate, $$NH_4NO_3$$

D
Guanidine, $$HNC(NH_2)_2$$

Solution

Compound %N
Urea $$(NH_2)_2CO$$   $$ 28\times\: \dfrac{100}{60} = 46.67%$$

Ammonia $$NH_3$$    $$ 14\times \dfrac{100}{17} = 82.35% $$

Ammonium nitrate $$NH_4NO_3      $$   $$  28\times {100}{80} = 35% $$

Guanidine $$HNC(NH_2)_2$$    $$ 42\times {100}{59} = 71.18% $$
Hence, the least expensive will be Ammonium nitrate $$NH_4NO_3$$.

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Some Basic Concepts of Chemistry Test - 22

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Some Basic Concepts of Chemistry Test - 22

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Question 1

Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.

Assertion is correct but Reason is incorrect.

Assertion is incorrect but Reason is correct.

Both assertion and reason are incorrect.

Solution

Question 2

5.6 L

11.2 L

22.4 L

44.8 L

Solution

Question 3

2 : 6 : 4 : 3

2 : 7 : 2 : 5

3 : 4 : 4 : 6

2 : 7 : 4 : 6

Solution

Question 4

1.992$$\displaystyle \times 10^{-23}$$ gm

1.989$$\displaystyle \times 10^{-23}$$ gm

1.892$$\displaystyle \times 10^{-23}$$ gm

1.965$$\displaystyle \times 10^{-23}$$ gm

Solution

Question 5

27 : 13

10 : 19

10 : 13

10 : 14

Solution

Question 6

the total mass of reactants, barium chloride, and sodium sulphate taken is greater than the total mass of products, barium sulphate, sodium chloride formed

the total mass of reactants, barium chloride, and sodium sulphate is less than the total mass of products, barium sulphate, and sodium chloride

the total mass of the reactants is equal to the total mass of products

none of the above

Solution

Question 7

Law of constant proportions

Law of conservation of energy

Law of conservation of mass

Law of multiple proportions

Solution

Question 8

$$1.66053892 10^{-27} kg$$

$$1.66053892 10^{-29} kg$$

$$1.23457656 10^{-27} kg$$

$$1.23457656 10^{-29} kg$$

Solution

Question 9

C-12 isotope

hydrogen

oxygen

nitrogen

Solution

Question 10

Urea, $$(NH_2)_2CO$$

Ammonia, $$NH_3$$

Ammonium nitrate, $$NH_4NO_3$$

Guanidine, $$HNC(NH_2)_2$$

Solution

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