Identity each of the following catalysts as
homogeneous or heterogeneous.
the addition of a strip of solid platinum metal to an
aqueous solution of hydrogen peroxide increases
the reaction rate of the decomposition reaction

Platinum is a Heterogeneous catalyst  

Explanation:

Catalyst are substance that speed up the rate of a chemical reaction . Catalyst increases the rate of a chemical reaction by lowering it activation energy. During the reaction, the catalyst are not consumed. In other words, catalyst does not change in amount as it does not go into the reaction.

Catalyst can be homogeneous or heterogeneous . A homogeneous catalyst is one which phase(liquid or gas) is same as the reactant phase. Heterogeneous catalyst are catalyst which phase(solid) is different from the reactants phase.      

From the reaction above

2H2O(aq)    Pt(s)→    2H2O(l) + O2(g)

Platinum is at the solid phase which is a different phase from the reactant(Hydrogen peroxide) which is Aqueous.

Since platinum is of a different phase , it is a heterogeneous catalyst.  

so here we go

atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer

the correct answer is b. a strong acid completely dissociates to its ions when dissolved in water. completely dissociates to and ions. a is incorrect because does not fully ionize to and ions and some remain as the compound . c and d are incorrect because, and do not fall into the category of bronsted lowry acids. a bronsted lowry acid is a proton donor and since both molecules do not have a proton to donate they are not bronsted lowry acids. likewise,   if we use the lewis acid definition, they cannot be acids. a lewis acid is an electron pair acceptor. both and have a complete octet so can not accept any electrons which disqualifies them as acids.