Chemistry
Assertion (A): In the laboratory preparation of hydrogen, granulated zinc is reacted with dilute acid.
Reason (R): Granulated zinc contains copper as an impurity.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Answer
Both A and R are true but R is not the correct explanation of A.
Explanation — In the laboratory, hydrogen is commonly prepared by reacting granulated zinc with a dilute acid (dil. HCl / dil. H2SO4). So, Assertion (A) is true.
Granulated zinc may contain small impurities such as copper, which can help the reaction start faster. So, Reason (R) is true.
However, Reason (R) is not the correct explanation of Assertion (A) as granulated zinc is mainly used because its rough, uneven surface provides larger effective surface area, so hydrogen is evolved at a steady and controllable rate.
Related Questions
Water gas is a mixture of
- carbon monoxide and oxygen
- carbon monoxide and hydrogen
- hydrogen and oxygen
- hydrogen and nitrogen
Assertion (A): On the earth, hydrogen is mostly found in the form of compounds.
Reason (R): Hydrogen is a highly reactive element.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): Pure hydrogen burns with a pop sound in air.
Reason (R): Hydrogen forms an explosive mixture with air.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A): Hydrogen is used for the extraction of less reactive metals like copper and lead.
Reason (R): Hydrogen is a good reducing agent.
- Both A and R are true and R is the correct explanation of A.
- Both A and R are true but R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.