Science
When 2 mL of sodium hydroxide solution is added to few pieces of granulated zinc in a test tube and then warmed, the reaction that occurs can be written in the form of a balanced chemical equation as :
options
- NaOH + Zn → NaZnO2 + H2O
- 2NaOH + Zn → Na2ZnO2 + H2
- 2NaOH + Zn → NaZnO2 + H2
- 2NaOH + Zn → Na2ZnO2 + H2O
Answer
2NaOH + Zn → Na2ZnO2 + H2
Reason — When a few pieces of granulated zinc are added to about 2 mL of sodium hydroxide solution in a test tube and the mixture is warmed, a chemical reaction takes place in which bubbles of hydrogen gas are evolved.
This happens because zinc is an amphoteric metal, meaning it can react with both acids and bases so in this case, zinc reacts with the strong base sodium hydroxide to form a soluble compound called sodium zincate and hydrogen gas.
The reaction can be represented by the balanced chemical equation:
2NaOH + Zn → Na2ZnO2 + H2
Related Questions
Select from the following a decomposition reaction in which source of energy for decomposition is light:
options
- 2FeSO4 → Fe2O3 + SO2 + SO3
- 2H2O → 2H2 + O2
- 2AgBr → 2Ag + Br2
- CaCO3 → CaO + CO2
A metal and a non-metal that exists in liquid state at the room temperature are respectively:
options
- Bromine and Mercury
- Mercury and Iodine
- Mercury and Bromine
- Iodine and Mercury
Carbon compounds :
(a) are good conductors of electricity.
(b) are bad conductors of electricity.
(c) have strong forces of attraction between their molecules.
(d) have weak forces of attraction between their molecules.
The correct statements are:
options
- (a) and (b)
- (b) and (c)
- (b) and (d)
- (a) and (c)
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FeSO4; CuSO4; CaSO4; Na2CO3
The compound having maximum number of water of crystallisation in its crystalline form in one molecule is :
options
- FeSO4
- CuSO4
- CaSO4
- Na2CO3