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प्रश्न
What do you observe when a piece of sodium is dropped into cold water?
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उत्तर
When a piece of sodium metal dropped in cold water we observe: Sodium floats on water surface melts forming a silvery globule which darts about the surface of water catches fire and burns with golden yellow flame.
Bubbles of hydrogen evolve and solution is soapy, slightly warm (alkaline) hence turns red litmus blue.
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संबंधित प्रश्न
Indicate which of the following statement is true and which is false:
Hydrogen gas is easily liquefiable.
Complete and balance the following equation:
H2+____________→ 2HCI
Give reason for the following:
Helium replaced hydrogen in weather observation balloons?
State four uses of hydrogen:
MULTIPLE CHOICE QUESTIONS
Which is the lightest of all elements?
- hydrogen
- helium
- lithium
- none of these
Write the balanced equation and give your observation when the following metal reacts:
Calcium with cold water
Write the balanced equation and give your observation when the following metal reacts:
Magnesium with boiling water
Choose the correct option:
The composition of the nucleus of deuterium is
Correct the following statement:
Hydrogen is dried by passing it through conc. H2SO4.
Give a test to differentiate between two gas jars – one containing pure hydrogen and the other hydrogen-air mixture.
With reference to the equation : Cl2 + H2S → 2HCl + S pertaining to a redox reaction – select the correct answer.
Chlorine is ______ to HCl.
Give balanced equation for the following conversion:
Nitrogen to a basic gas – using hydrogen.
Give reason for the following:
The reaction of chlorine with hydrogen sulphide is deemed a redox reaction.
Write a correctly balanced equation for the following “word equation”:
calcium + water → calcium hydroxide + hydrogen
Name a gas which burns in air or oxygen forming water.
Describe one chemical test applied to the following gases, which would enable you to distinguish between them :‘carbon monoxide and hydrogen’.
Write down the “word equation” for the following reaction:
sodium hydroxide solution + zinc → ?
Write balanced equation of the reaction in the preparation of : hydrogen from a solution of potassium hydroxide [other than by electrolysis].
Give balanced equation for obtaining hydrogen from cold water using a divalent active metal.
