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 – Thermal decomposition of mercury [II] oxide.
Advertisements
Solution
Thermal decomposition of mercury [II] oxides: Red colour of Hg[II]0 changes to silvery (Hg metal).
APPEARS IN
RELATED QUESTIONS
When carbon dioxide is passed through lime water, it turns milky due to the formation of ______.
What do you observe when Iron nail is kept in copper sulphate solution for sometime.
MULTIPLE CHOICE QUESTIONS
Tick the most appropriate answer.
Reduction reaction is the exact opposite of
- displacement reaction
- decomposition reaction
- oxidation reaction
- none of these
FILL IN THE BLANK
A .............. change is a temporary change.
TRUE \ FALSE
The evolution of a gas during a chemical reaction is shown by an arrow pointing downwards. True or false ?
How is a strong electrolyte different from a weak electrolyte?
Fill in the blank.
Melting of ice is a _______ change.
Fill in the blank:
The substances which undergo chemical change are called _______
Complete the statement by filling the gaps using appropriate term from the terms given in the bracket.
(slow, coloured, arrow, fast, smell, milky, physical, product, chemical, reactant, covalent, ionic, octet, duplet, exchange, sharing, equality sign)
Rusting of iron is a ______ chemical change.
State the type of reactions for the following represent and balance the ones that are not balanced.
NaOH + HCl → NaCl + H2O
What do you observe? When
Water is added to the quick lime.
Give a chemical test to distinguish between the following gases.
NH3 and HCl
Give a word equation for the following reaction.
Two solids which combine on heating, to give a liquid.
Give balanced equation for the following conversion affected by heat alone on the substance:
Zinc carbonate to zinc oxide
Complete the table given below.
| Heat on iodine crystals | Colour of vapours evolved |
Chemical change is a temporary change.
Write the chemical reaction of baking soda with lemon.
Write five changes in the characteristics of a substance that can take place during a chemical change.
Both CO2 and H2 gases are ______.
Acid rain is a result of ______.
