Which of the following is not an endothermic reaction?
CaCO3 → CaO + CO2
2H2O → 2H2 + O2
6CO2 + 6H2O → C6H12O6 + 6O2
C6H12O6 + 6O2 → 6CO2 + 6H2O
Which of the following does not involve a chemical reaction?
digestion of food in our body
process of respiration
burning of candle wax when heated
melting of candle wax on heating
The reaction in which two compounds exchange their ions to form two new compounds is called
A displacement reaction
A decomposition reaction
An isomerisation reaction
A metathesis reaction
Oil and fat containing items are flushed with nitrogen for preventing
Burning
Rancidity
Neutralisation
Rusting
When copper powder is heated it gets coated with-
Black copper oxide
Yellow copper oxide
Red copper oxide
None of these
An acid which can decolourise purple coloured potassium permanganate solution is:
sulphuric acid
citric acid
carbonic acid
hydrochloric acid
Silver chloride turns grey
On heating
On cooling
In sunlight
At room temperature
If a substance gains oxygen during a reaction, it is said to be
Reduced
Oxidised
Reversed
Irreversible
When hydrogen sulphide gas is passed through a blue solution of copper sulphate, a black precipitate of copper sulphate, a black precipitate of copper sulphide is obtained and the sulphuric acid so formed remains in the solution. The reaction is an example of
A combination reaction
A double decomposition reaction
A solution of _____________ is used for white washing walls.
Slaked lime
Soda lime
Soda ash
Caustic potash
