<u>Answer:</u> The correct option is
<u>Explanation:</u>
A catalyst is defined as the chemical species that increases the reaction rate but does not participate in it and is left behind after the completion.
A homogeneous catalyst is one that is present in the same phase as the reactants and products.
A heterogeneous catalyst is one that is present in different phase as that of reactants and products.
For the given chemical reaction:

As all the reactants and products are in gaseous state so, the homogeneous catalyst must also be in the gaseous state only.
Hence, the correct option is 
Hard water contains high levels of minerals such as magnesium and calcium and can be a real pain to remove if left untreated. When hard water is boiled in an electric kettle, these minerals do not evaporate like the water does but instead remains in the kettle.
Answer:
there are 35.7 mol H in 1.70 mol benadryl
Explanation:
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Use formula: Initial Pressure x Initial Volume/Initial temperature = Final pressure x Final Volume/Final Temperature => 17.15L