Advertisements
Advertisements
प्रश्न
Which of the following are chemical changes?
(i) Decaying of wood
(ii) Burning of wood
(iii) Sawing of wood
(iv) Hammering of a nail into a piece of wood
पर्याय
(i) and (ii)
(ii) and (iii)
(iii) and (iv)
(i) and (iv)
Advertisements
उत्तर
(i) and (ii)
Explanation:
Decaying of wood and burning of wood are chemical changes since there is a change in the chemical composition of wood. Sawing of wood and hammering of a nail into a piece of wood are physical changes since there is no change in the composition of the wood during these changes.
APPEARS IN
संबंधित प्रश्न
Distinguish by heating the following in dry test tubs.
Zinc carbonate, Copper carbonate and lead carbonate.
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.
On heating which of the following substances i.e. copper carbonate, zinc carbonate, washing soda, copper sulphate, zinc nitrate, copper nitrate, lead nitrate, ammonium chloride and ammonium dichromate – relate to the reaction given below.
A coloured substance which leaves a black residue and evolves two gases one of which is acidic and coloured and the other neutral and colourless.
Complete the table given below.
| Heat on Zinc nitrate | Colour of residue |
Complete the table given below.
| Addition of dil. H2SO4 to zinc | Test for gas evolved |
Give a balanced equation for the conversion of an ammonium salt to a basic gas.
Iron benches kept in lawns and gardens get____________. It is a _________ change because a new _________ is formed.
A student took a solution of copper sulphate in a beaker and put a clean iron nail into it and left it for about an hour.
Write a word equation for the chemical change, if any.
The chemical name of baking soda is sodium bicarbonate.
What is the difference between reactants and products?
