Science
Assertion (A) : On adding dil. HCl to a test tube containing a substance ‘X’, a colourless gas is produced which gives a pop sound when a burning match stick is brought near it.
Reason (R) : In this reaction metal ‘X’ is displaced by Hydrogen.
options
- Both A and R are true, and R is the correct explanation of A.
- Both A and R are true, and R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Answer
A is true but R is false.
Reason —
Assertion (A) is true because when dilute hydrochloric acid (HCl) is added to a substance ‘X’, a colourless gas is evolved that produces a pop sound when a burning matchstick is brought near it. The gas is hydrogen (H2), which is released when a metal reacts with an acid and the pop sound confirms the presence of hydrogen gas.
Reason (R) is false because in this reaction the metal 'X' displaces hydrogen from the acid as metals are more reactive than hydrogen and the displaced hydrogen is released as a gas.
Hence, (A) is true, but (R) is false.
Related Questions
Identify the incorrect statement
‘The energy available to the producers is maximum’ because:
options
- It is the first trophic level which absorbs 1% of light energy directly from the source.
- It utilizes the most of the chemical energy for its own respiration, growth, reproduction, movement etc.
- It utilizes 10% of light energy and transfers the rest to the next trophic level.
- It transfers only 10% of light energy to the next trophic level
Which of the following is not a role of decomposers in the ecosystem?
options
- Natural replenishment of soil.
- Enrichment of oxygen in atmosphere.
- Waste decomposition.
- Break-down of dead remains.
Assertion (A) : Generally, the number of chromosomes in a cell and in a germ cell is not the same in species.
Reason (R) : When two germ cells combine, they restore the normal number of chromosomes in a species.
options
- Both A and R are true, and R is the correct explanation of A.
- Both A and R are true, and R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.
Assertion (A) : A convex mirror always forms an image behind it and the image formed is virtual.
Reason (R) : According to the sign convention, the focal length of a convex mirror is positive.
options
- Both A and R are true, and R is the correct explanation of A.
- Both A and R are true, and R is not the correct explanation of A.
- A is true but R is false.
- A is false but R is true.