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प्रश्न
Name the gases which turn moist red litmus blue.
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उत्तर
Basic gases (NH3)
संबंधित प्रश्न
How do the following help in bringing about a chemical change?
catalyst .
FILL IN THE BLANK
Positively charged ions are called ........
Define an electrochemical reaction.
Give an example of the following chemical change.
Two solids combine to form a liquid
Name: Two nitrates that do not produce nitrogen dioxide on heating.
Distinguish by dilute sulphuric acid.
Copper and magnesium?
Give reason for the following:
Even though rusting is an exothermic reaction, the heat evolved when an iron nail rusts is unnoticeable.
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.
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 on strong heating a black residue and evolves two colourless gases one of which is acidic and the other neutral.
A bag of cement lying in the open gets wet due to rain during the night. The next day the sun shines brightly. Do you think the changes, which have occurred in the cement, could be reversed?
