Chemistry
Assertion (A): Oxyhydrogen flame is used for cutting and welding metals.
Reason (R): For cutting and welding metals, a low temperature is required.
- 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.
Hydrogen
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Answer
A is true but R is false.
Explanation — Oxyhydrogen flame is used for cutting and welding metals. So, Assertion (A) is true.
For cutting and welding metals, a high temperature is required. Oxyhydrogen flame has a temperature of about 2800°C-3000°C, which is sufficient to melt the metals. So, Reason (R) is false.
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Related Questions
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.
Fill in the blanks:
(a) Hydrogen is …………… than air.
(b) Hydrogen is …………… soluble in water.
(c) Hydrogen burns with a …………… flame and …………… sound is heard.
(d) A metal …………… hydrogen in the reactivity series gives hydrogen with …………… .
(e) Hydrogen reacts with metal oxides to form …………… and …………… .
(f) Oxidation is the removal of …………… or addition of …………… .
(g) In redox reactions, oxidation and reduction occurs …………… .
Indicate which of the following statements are true and which are false:
(a) Hydrogen molecule is monovalent.
(b) The removal of hydrogen from a substance is called reduction.
(c) Nitric acid cannot be used to prepare hydrogen by its action on active metals.
(d) The reaction between hydrogen and nitrogen to form ammonia is reversible.
(e) Zinc can liberate hydrogen from water, acid and alkali solution.
(f) Hydrogen is combustible as well as a supporter of combustion.
(g) Hydrogen gas is easily liquefiable.