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Science Assertion - Reasoning [Che-1 M]

Atoms and Molecules · CBSE STD 9 (CBSE - English Medium). 5 questions.

Questions

Assertion - Reasoning [Che-1 M]

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5 questions · self-marked practice — reveal the answer and mark yourself.

Question 11 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:
  1. Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.
  2. The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
  3. Assertion is true but the Reason is false
  4. The statement of the Assertion is false but the Reason is true.
Assertion: The formula of aluminium sulphate is Al2(SO4)3.
Reason: The valency of Al is 3 and charge on SO42-.
Answer
  1. Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.

Explanation:

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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Question 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:

  1. Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.
  2. The Assertion and the Reason are correct but the Reason is not the correct explanation of the Assertion.
  3. Assertion is true but the Reason is false
  4. The statement of the Assertion is false but the Reason is true.

Assertion: 23g of Na contains 6.022 × 1023 sodium atoms.

Reason: 23g of Na contains 1 atom of Na.

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

Explanation:

One mole contains 6.023 × 1023 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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Question 31 Mark
In the following questions, a statement of assertion (A) is followed by a statement of reason (R).
Mark the correct choice as:
  1. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  2. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
  3. If Assertion is true but Reason is false.
  4. If Assertion is false and Reason is true.
  5. If both Assertion and Reason are false.
Assertion: When 10g of Caco3 is decomposed, 5.6g of residue is left and 4.4g of CO2 escapes.
Reason: Law of conservation of mass is followed.
Answer
  1. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.

Explanation:

5.6g residue will be left as due to law of conservation of mass

Total mass of CaCO3 = Mass of CO2 + 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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Question 41 Mark
In the following questions, a statement of assertion (A) is followed by a statement of reason (R).
Mark the correct choice as:
  1. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  2. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
  3. If Assertion is true but Reason is false.
  4. If Assertion is false and Reason is true.
  5. If both Assertion and Reason are false.
Assertion: SI unit of atomic mass and molecular mass is kg.
Reason: It is equal to the mass of 6.023 × 1023 atoms.
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Question 51 Mark
In the following questions, a statement of assertion (A) is followed by a statement of reason (R).
Mark the correct choice as:
  1. If both Assertion and Reason are true and Reason is the correct explanation of Assertion.
  2. If both Assertion and Reason are true but Reason is not the correct explanation of Assertion.
  3. If Assertion is true but Reason is false.
  4. If Assertion is false and Reason is true.
  5. If both Assertion and Reason are false.
Assertion: Atomicity of O3 is 3.
Reason: 1 mole of an element contains 6.023 × 1023 atoms.
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Assertion - Reasoning [Che-1 M] - Science STD 9 Questions - Vidyadip