Which of the following is not an endothermic reaction?
CaCO3 → CaO + CO2
2H2O → 2H2 + O2
6CO2 + 6H2O → C6H12O6 + 6O2
C6H12O6 + 6O2 → 6CO2 + 6H2O
What happens when dilute hydrochloric acid is added to iron fillings?
Hydrogen gas and iron chloride are produced.
Chlorine gas and iron hydroxide are produced.
No reaction takes place
Iron salt and water are produced
Which of the following is a displacement reaction?
NaOH + HNO3 → NaNO3 + H2O
Cu + 2AgNO3 → Cu(NO3)2 + 2Ag
2Hg + O2 → 2HgO
FeCl3 + 3NaOH → 3NaCl + Fe(OH)3
In the following equations
Na2CO3 + xHCl → 2NaCl + CO2 + H2O the value of x is
1
2
3
4
Which of the following reactions involves the combination of two elements?
CaO + CO2 → CaCO3
4Na + O2 → 2Na2O
SO2 + O2 → SO3
NH3 + HCl → NH4Cl
The chemical reaction between quicklime and water is characterised by:
evolution of hydrogen gas
formation of slaked lime precipitate
change in temperature of mixture
change in colour of the product
A solution of _____________ is used for white washing walls.
Slaked lime
Soda lime
Soda ash
Caustic potash
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 displacement reaction
A decomposition reaction
A double decomposition reaction
One of the following does not happen during a chemical reaction. This is :
breaking of old chemical bonds and formation of new chemical bonds
formation of new substances with entirely different properties
atoms of one element changes into those of another element to form new products
a rearrangement of atoms takes place to form new products
The equation
Cu + XHNO3 → Cu(NO3)2 + YNO2 + 2H2O the values of X and Y are
3 and 1
8 and 6
4 and 2
7 and 1 respectively