Which of the following observations helps to determine whether a chemical reaction has taken place or not?
(i) Change in state.
(ii) Change in colour.
(iii) Change in shape
(iv) Evolution of gas.
(v) Change in temperature.
Which of the following observations helps to determine whether a chemical reaction has taken place or not?
(i) Change in state.
(ii) Change in colour.
(iii) Change in shape
(iv) Evolution of gas.
(v) Change in temperature.
The correct option is B (i), (ii), (iv), (v)
The observations that help us for determining a chemical reaction are:
(a) Change in state ( Electrolysis of water in a liquid state gives off oxygen and hydrogen gases )
(b) Change in colour ( When sugar is heated it turns brown )
(c) Evolution of gas ( Ferric sulphate on heating gives ferric oxide and sulphur dioxide and sulphur trioxide gases are evolved).
(d) Change in temperature ( When water is added to quick lime, temperature of the mixture increases )
# change in shape is a physical reaction (ex: cutting of wood )
(i), (ii), (iv), (v)
The observations that help us for determining a chemical reaction are:
(a) Change in state ( Electrolysis of water in a liquid state gives off oxygen and hydrogen gases )
(b) Change in colour ( When sugar is heated it turns brown )
(c) Evolution of gas ( Ferric sulphate on heating gives ferric oxide and sulphur dioxide and sulphur trioxide gases are evolved).
(d) Change in temperature ( When water is added to quick lime, temperature of the mixture increases )
# change in shape is a physical reaction (ex: cutting of wood )
