Answer:
When popcorn is popped, liquid inside the kernel is changed to steam. Pressure from the steam builds up inside the kernel. When the pressure reached a critical stage the kernel pops turning itself inside out. This is a physical change.
Explanation:
Answer:
20.0928.
Explanation:
The average atomic mass is (90 * 19.992 + 10* 21) / 100
= 20.0928.
A fact can be disapproved with further evidence different details. So basically evidence can change a fact!! Hope this helps
i. The dissolution of PbSO₄ in water entails its ionizing into its constituent ions:

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ii. Given the dissolution of some substance
,
the Ksp, or the solubility product constant, of the preceding equation takes the general form
.
The concentrations of pure solids (like substance A) and liquids are excluded from the equilibrium expression.
So, given our dissociation equation in question i., our Ksp expression would be written as:
.
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iii. Presumably, what we're being asked for here is the <em>molar </em>solubility of PbSO4 (at the standard 25 °C, as Ksp is temperature dependent). We have all the information needed to calculate the molar solubility. Since the Ksp tells us the ratio of equilibrium concentrations of PbSO4 in solution, we can consider either [Pb2+] or [SO4^2-] as equivalent to our molar solubility (since the concentration of either ion is the extent to which solid PbSO4 will dissociate or dissolve in water).
We know that Ksp = [Pb2+][SO4^2-], and we are given the value of the Ksp of for PbSO4 as 1.3 × 10⁻⁸. Since the molar ratio between the two ions are the same, we can use an equivalent variable to represent both:

So, the molar solubility of PbSO4 is 1.1 × 10⁻⁴ mol/L. The answer is given to two significant figures since the Ksp is given to two significant figures.
4 moles of NaCl is produced from 2 moles of Na₂CrO₄.
<u>Explanation:</u>
Given reaction is
PbCl₂(aq) + Na₂CrO₄(aq)→ PbCrO₄(s) + 2 NaCl (aq)
It is the balanced equation which means that on both sides of the equation, number of atoms of each element are equal.
From the above balanced equation it says that molar ratio of Na₂CrO₄ to NaCl is 1 : 2.
That is 1 mole of Na₂CrO₄ produces 2 moles of NaCl, so the molar ratio is 1:2.
2 moles of Na₂CrO₄ produces 4 moles of NaCl.
So the molar ratio of Na₂CrO₄ to NaCl is 2: 4.