Assertion (A) & Reason (B) MCQ

Question 11 Mark

In the following questions, a statement of assertion $(A)$ is followed by a statement of reason $(R)$. Mark the correct choice as:

If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
If Assertion is true but Reason is false.
If Assertion is false and Reason is true.
If both Assertion and Reason are false.

Assertion: Atomicity of $O_3$ is $3$.
Reason: $1$ mole of an element contains $6.023 \times 10^{23}$ atoms.

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MCQ 21 Mark

In the following Questions, the Assertion and Reason have been put forward. Read the statements carefully and choose the correct alternative from the following:
Assertion: $23g$ of Na contains $6.022 \times 10^{23}$ sodium atoms.
Reason: $23g$ of Na contains $1$ atom of Na.

✓
Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.
B
The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
C
Assertion is true but the Reason is false
D
The statement of the Assertion is false but the Reason is true.

Answer

Correct option: A.

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

One mole contains $6.023 \times 10^{23}$ chemical units.
$23g$ of Na atom
atomic mass of $Na = 23u$
Number of particles=Number of Moles$ × N$
$\Rightarrow\Big(\frac{\text{Given weight}}{\text{Gram atomic weight}}\Big)\times6.023\times10^{23}$
$\Rightarrow\Big(\frac{23}{23}\Big)\times6.023\times10^{23}$
$\Rightarrow1\times6.023\times10^{23}$
$\Rightarrow6.023\times10^{23}$ Na particles

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MCQ 31 Mark

In the following questions, a statement of assertion $(A)$ is followed by a statement of reason $(R)$.
Mark the correct choice as:
Assertion: When $10g$ of $Caco_3$ is decomposed, $5.6g$ of residue is left and $4.4g$ of $CO_2$ escapes.
Reason: Law of conservation of mass is followed.

✓
If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
B
If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
C
If Assertion is true but Reason is false.
D
If Assertion is false and Reason is true.

Answer

Correct option: A.

If both Assertion and Reason are true and Reason is the correct explanation of Assertion.

5.6g residue will be left as due to law of conservation of mass
Total mass of $CaCO_3 =$ Mass of $CO_2 +$ mass Mass of $× (CaO)$
$= 10.0 = 4.4 + ×$
$= × = 10.0 - 4.4$
Hence, $x = 5.6$
Hence the mass of $CaO$ is $5.6$ gram.

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MCQ 41 Mark

In the following Questions, the Assertion and Reason have been put forward. Read the statements carefully and choose the correct alternative from the following:
Assertion: The formula of aluminium sulphate is $Al_2(SO_4)_3$.
Reason: The valency of $Al$ is $3$ and charge on $SO_4{}^{2-}$.

✓
Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.
B
The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
C
Assertion is true but the Reason is false
D
The statement of the Assertion is false but the Reason is true.

Answer

Correct option: A.

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

$Al2 (SO4)_3$ is commonly known as aluminium sulphate.
There is two aluminium atom in aluminium sulphate, and because of this, the total valency of the formula is $6^+$.
Aluminium make positively charged ions, which makes the sulphate to have negatively charged ions.
Therefore, the valency of sulphate will be $2^-$ and aluminium is $3^+$ in aluminium sulphate.

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