Advertisements
Advertisements
Question
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- Formation of a precipitate.
With reference to each of the above indications, state the external indication seen during – Addition of dilute acid to an active metal.
Advertisements
Solution
Addition of dil. acid to an active metal: Gas is evolved, test tube or flask becomes hot (heat is produced).
APPEARS IN
RELATED QUESTIONS
When carbon dioxide is passed through lime water, it turns milky due to the formation of ______.
The gas we use in the kitchen is called liquefied petroleum gas (LPG). In the cylinder, it exists as a liquid. When it comes out from the cylinder it becomes a gas (Change − A), then it burns (Change − B). The following statements pertain to these changes. Choose the correct one.
Complete and balance the following chemical equations
NaCI + `AgNO_3` `→`
Classify the following reaction as combination, decomposition, displacement, precipitation and neutralization. Also balance the equation.
\[\ce{NH3_{(g)} + HCl_{(g)} -> NH4Cl_{(s)}}\]
FILL IN THE BLANK
Positively charged ions are called ........
Define electrolysis.
What do you observe when :
an iron nail is kept in tap water for few days
State four conditions necessary for a chemical reaction to take place.
Name the type of chemical reaction shown by the following equation:
2Mg + O2 → 2MgO
Show with the help of diagram of electronic configuration how the following compound is formed from the constituent atoms.
Sodium chloride
When electric current is passed through acidulated water ______ of water takes place.
Give an example of a reaction where the following are involved
Heat
State the type of reactions for the following represent and balance the ones that are not balanced.
NaOH + HCl → NaCl + H2O
Name: Two nitrates that do not produce nitrogen dioxide on heating.
State the original colour of the following substance and colour of residue obtained after heating.
Zinc carbonate
Give a chemical test to distinguish between the following gases.
NH3 and HCl
Give a chemical test to distinguish between the following gases.
NH3 and SO2
A chemical reaction is often accompanied by external indications or characteristics which include –
- Colour change
- Effervescence or gas evolved
- Evolution or absorption of heat
- Formation of a precipitate.
With reference to each of the above indications, state the external indication seen during – Thermal decomposition of mercury [II] oxide.
Explain with the help of balanced equations, how precipitation reactions are used for identifying the positive radicals in three different salts, each having a different cation [positive ion].
Differentiate between the following:
Neutralization reaction and a precipitation reaction.
