Answer:
1 mole of platinum
Explanation:
To obtain the number of mole(s) of platinum present, we need to determine the empirical formula for the compound.
The empirical formula for the compound can be obtained as follow:
Platinum (Pt) = 117.4 g
Carbon (C) = 28.91 g
Nitrogen (N) = 33.71 g
Divide by their molar mass
Pt = 117.4 / 195 = 0.602
C = 28.91 / 12 = 2.409
N = 33.71 / 14 = 2.408
Divide by the smallest
Pt = 0.602 / 0.602 = 1
C = 2.409 / 0.602 = 4
N = 2.408 / 0.602 = 4
The empirical formula for the compound is PtC₄N₄ => Pt(CN)₄
From the formula of the compound (i.e Pt(CN)₄), we can see clearly that the compound contains 1 mole of platinum.
Answer:
Pre-zygotic, temporal separation
Explanation:
Reproductive isolation mechanism is of two types:
- Prezygotic mechanism
- Postzygotic mechanism
Prezygotic mechanism isolation occurs before fertilization and helpful in preventing formation of fertile offspring.
In frog external fertilization occurs. In the external fertilization, eggs and sperms are released in water and fertilization occur outside the water.
Prezygotic isolating mechanisms may include behavioral isolation, temporal isolation, mechanical isolation, gametic isolation and habitat isolation.
Temporal separation in reproduction is the sexual activity in the same geographical range but in different periods.
Therefore, the given reproductive isolation is pre-zygotic, temporal separation.
Mass of H₂ needed to react with O₂ : 1.092 g
<h3>Further explanation</h3>
The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight / volume,), molarity, molality, parts per million (ppm) or mole fraction. The concentration shows the amount of solute in a unit of the amount of solvent.
Reaction
O₂(g) + 2H₂(g) → 2H₂O(g)
mass of O₂ : 8.75 g
mol O₂(MW=32 g/mol) :
From the equation, mol ratio of O₂ : H₂ = 1 : 2, so mol H₂ :
Mass H₂ (MW=2 g/mol) :
Answer:
Choice A.
A low birth to death ratio
Explanation:
A low birth to death ratio means that people are dying faster than they are being born. This leads to a decreasing population size.
